Might be the same as Witcher 4 if the MC ended the first game with god tier powers/items?

Well it's complicated, there are multiple endings including at least one recognized as a "bad ending", but in general it's more like Geralt and Ciri, his daughter that has grown up, overcome the mortal dangers together with the important people around them.

However the god tier powers in the story were the ones Ciri was born with, so the motivation can't really be the same with this move here. It's probably just that it makes sense to tell the next part of Ciri's story directly from her perspective now.