I think it depends on the brand.

Campagnolo presses their sealed bearings onto the crank spindle, and the bearing cups on the bike stay in place. You need a puller to free the bearings from the cranks.

I think Wheels Manufacturing also uses a type of bearing cups with replaceable bearings.

Some of the internal press fit bearings are mainly just bearings that must be removed and replaced.

I think the MegaExo bottom bracket is usually a sealed unit that must be removed and discarded, often screw-in for English threads. Get a special wrench to unscrew it.

With the proper wrench, the repair can be done by anybody.