How do we fix a charge(+ve or -ve) in a given position in electrostatics?

I know that we assume that we fix a charge by some unspecified force(but what are they , explain with some example )

Like what are the possible ways to do it with/without affecting other configurations of the charges in the surrounding

How do we fix a charge  (positive or negative) in a given position in electrostatics?

I know that we assume that we fix a charge by some unspecified force, but what are they? Please explain with some example.

Like what are the possible ways to do it with/without affecting other configurations of the charges in the surrounding