plate squeeze is a great exercise for developing the chest, especially if you struggle with forearm strength and endurance.
make sure you point your fingers out and bend your elbow slightly(and just a few degrees) and hold it like that.
for adding overload, try using three or four plates instead of adding weight.
the more you add weight by choosing heavier plates, the more you use your front delt or shoulder muscle instead of the chest.
the goal for this exercise is not to lift the weight up and down, but to stabilize the plates while going up and down to target different fibers. so make sure you slow the pace and speed as well(i demonstrate the exercises faster for time management).