Depends how old and what mount/functionality you want.
Really old Canon FD lenses for example you’d just need something cheap like this:
https://www.amazon.co.uk/Beschoi-Ad...fd-e+mount&dpPl=1&dpID=41AVWsY78UL&ref=plSrch
Clearly it’s basically a metal tube and you’d only have the metadata recorded by the camera (no lens data).
If you wanted to use for example the Minolta Beercan and you wanted the AF and aperture you would need the much more expensive LA-EA3/4.
So all depends on the lenses basically