Not in most cases. Apple, AMD, and most other chip makers lack a fab. The design what the fabs can make, but they don't have much input into the fabs. Someone makes a fab, and you make something it can made.

Of course things are never that neat. I have no doubt the large players have input into the fabs - we have no idea what. However the two teams are still different companies, when the fab and chip design are the same company there is the possibility of more cooperation (or less - we don't know. In the best case for both there is more when it is all internal, but we don't know if this is the best case)