Consider a dielectric sphere placed within a dielctric medium. There is a uniform electric field $E_0$ present throughout in the medium.
Would there be surface charge on the sphere?
Yes, there will be a surface charge density on the sphere. Because, the field in the outer medium will polarize the molecules of the dielectric and thus, there will come some surface charge density on the sphere. Notice that the dielectric sphere would still remain electrically neutral as a whole. The electric density will appear because of the redistribution of the electric charge.