Are these sentences all OK?
I haven't seen a kid for a long time.

If I say;
Look how big you are!
Look how big got!
Look how you have grown!

Question

Are these sentences all OK?
I haven't seen a kid for a long time.

If I say;
Look how big you are!
Look how big got!
Look how you have grown!

Answer

There'll all fine, except for the second one, where you forgot "you". ("Look how big you got.")

Answer

Technically the second one should be 'look how big you have become'.  Yes, some  people are likely to use 'have got', but it doesn't sound good and isn't good English.