Does this work to reduce eyes strain? Enlarge the PC monitor with a lens I have an idea to reduce eyes strain, but don't know if it works.
I work by looking at PC monitor all day long and I believe my myopia condition is getting worse and eyes strain occurs are due to looking at the PC screen at close distance for long time everyday. So I come up with an idea that put the screen far away, like 6 meters from my eyes, because I have heard that when someone see things above 6 meters from their eyes then their eyes will be relaxed.
I am used to looking at my 24-inch PC screen at a dinstance of about 60 cm, long hours, everyday. Now I want to put it at a distance of 6 meters. But the problem is that I want the size of texts and photos remain the same, so I have to use a bigger screen, in this case it must be 24*(6/0.6) = 240 inch monitor. I can't afford such a monitor. Also my room is not big enough to put a big screen 6 meters away from my desk.
So I come up with this idea: using a lens to enlarge the screen. Let see my setup:

I put my real screen against the wall of my room, then I put a 1.5 diop lens 0.6 m away from the screen. Base on my knowledges about lens, I calculate that the virtual image of real screen would be 6 m away from the lens and the size of virtual screen would be 240 inches, all things match the requirements at the begining. So as long as my eyes stay in the hatched region and see through the lens, I will see a 240-inch screen at 6 m far away. Because the virtual screen is at 6 m far away, then my eyes will be relaxed. Does this work? The lens would be in rectangular shape and is nearly big as real screen.
Edit: I am myopic, I am wearing -2 dioptre glasses. These glasses is right glasses matching my myopia, it means with theses glasses I can see things at infinity with a maximum relaxation of my lenses (because the glasses create virtual images of things at infinity, these virtual images are at my furthest distance I can see without glasses). And I would like to wear my glasses in the photo above.
 A: Since you assume that the viewing angle of the virtual 240" screen at 6m is the same as your real 24" screen at 0.6m, what you require is nothing but an awkward description of wanting to wear appropriate glasses, because the purpose of glasses is to shift the focal plane only.
If you would require that the viewing angle should increase (the virtual screen appears bigger than in reality, in order to see details better), this would be equivalent to watching the screen through binoculars/telescope. However, binoculars typically require a substantial amount of glass, making them heavy and inconvenient. I am not familiar enough with optics to know whether PC binoculars can be fabricated at a convenient weight, e.g. with plastic lenses. But this wasn't your question anyway.
So, back to the first option, I would estimate that a normal-sighted person needs glasses with around +1 to +2 dioptres to see a screen that is actually at 0.6m at a virtual distance of infinity. That would allow this person a maximum relaxation of her lenses in the eyes. BTW, I use +1.5 dioptres before the PC, because I am presbyopic (i.e. I have a reduced accomodation width due to age).
Since you are myopic, you are already seeing things at virtual infinity which are actually at a finite distance (which is why you can't see things that are further away, because, colloquially speaking there is nothing further away than infinity). If your infinity-viewing-distance is even at 0.6m, then you would not need to do anything further if you want to relax your eyes, just take of your glasses, if you have any.
But if you are heavily myopic, then you would see infinity already closer than 0.6m (e.g. 0.5m), which would explain why watching your PC screen at 0.6m stresses you (it appears blurry). The appropriate measure would be to buy the right glasses matching your myopia (probably something beyond -2 dioptres?). If you do not want to see the doctor, you could try out cheap glasses from the supermarket (which are remarkably good, but they are scratch sensitive and suffer from reflexes because they usually do not have anti-reflective coating) with different dioptre ratings and see what works best.
Note, that this the opposite of what you are proposing (glasses for hyperopic, > 0 dioptres), because

...I have heard that when someone see things above 6 meters from their eyes then their eyes will be relaxed.

this is only true for normal-sighted persons, and not for you if you are myopic! Myopic persons need to look at things much closer to relax their eyes.
Some other things that affect strain on the eyes:

*

*if you need to look at things at a very short distance because you are myopic (say you can't help putting your screen at 30 cm), then you will have to turn your eyes much more inward, which strains the respective muscles. I don't know, but possibly this is not corrected by your glasses, although I think it would simply require an additional prismatic part of the glasses.

*relaxing the eyes all the time might be counterproductive, because the lenses of the eyes and the eyes' vitreous body have no blood vessels. Hence, they have to rely on movement/stretching in order to be properly supplied with nutrients/oxygen (and whatever they need to function biologically) through fluid interchange. So it is healthier for the eyes to strain and relax alternately, something which is difficult if you sit before the PC long hours.

A: About accomodation:
To bring nearby objects into focus the eye contracts a ring muscle. That contraction gives the lens of the eye room to contract to a more rounded shape. (Conversely, when that ring muscle relaxes ligaments around the lens pull the lens to a flatter shape.)
I gather you want to give your eyes maximum opportunity to be relaxed. For a person without any myopia that would make it necessary to place the monitor quite far away.
With myopic vision there are other options.
I am myopic, so there is a distance beyond which I cannot see sharp. That largest distance of being able to see sharp is the far end of the accomodation range of my eyesight. That is: at that point my eyes are not accomodating, hence the ring muscle that contracts to facilitate the accomodation is relaxed.
So if I want to relax my exes I should not wear my contacts, and place my monitor at the far end where I'm just still able to see sharp. (It so happens that personally I'm so highly myopic that that would be unpractical.)
My recommendation for something to try:
Wear contacts/glasses such that the farthest point that you can see sharp is about, say, a meter away from you, and position the monitor there. That is, try wearing contacts/glasses that undercorrect your myopia, such that a little bit of myopia remains.
The idea is to tailor the amount of undercorrection such that your eyes are relaxed when your attention is on the monitor.

As I stated earlier, I'm myopic. In addition: presbyopia has started for me. Now: at my workplace I have no need for distant vision, and I have found that the following works well for me: at my workplace I wear contacts that undercorrect my myopia, such that I don't need reading glasses. In a sense I am taking advantage of my myopia. My myopia gives me the option to undercorrect for it, whereas for someone without myopia using reading glasses is pretty much the only option.
(Of course, when driving a car I wear contacts/glasses that provide full correction.)
