Hi my employer made changes to T4 box 50 and 52, how does it impact my tax return. o already files 2018 return with zero in box 50 and 52

There is no box 50 on the T4, but box 52 is regarding pension adjustments. I would wait to receive your NOA before making any changes as they may have caught it in review as that amendment T4 was also given to the CRA.