Just replying with a web page showing the 80386 has having control registers doesn't imply that MS-DOS used them in any meaningful way.

The MMU is inside the processor. Any operating system running on an 80386 or higher has set registers/tables and gets hardware provided memory management.

If it uses it. Later versions of DOS did very little with the features the 386 offered, which is why there were MS-DOS extenders.

https://en.m.wikipedia.org/wiki/DOS_extender

You can make your own minimal DOS Extender just by setting those registers. This is what some games did.