I have 3/4" supply coming into my house. Then it get reduced to 1/2" almost right away. Is there any benefit to going 3/4" thought out my house? or going to a manifold with 3/4" then goto 1/2" what is the best way?

Typically you go from 3/4 main to 1/2 inch supply to each bathroom, utility room, kitchen, etc.

How many bathrooms?

You will be better off with 3/4" manifold, branching into several dedicated 1/2" supplies. 1/2" pipe by itself is not capable to carry typical bathroom as it has not enough volume to satisfy demand. Please, answer Mark's question so one of us can expand on this topic. Thank you. Milo