You asked
Can I use adapted lenses on the canon eos 850d?
The Canon EOS 850D uses the Canon EF mount, so the EF and EF-S lenses on its catalogue page fit directly, with no adapter. My pages don't cover adapting lenses from other mounts, so I can't tell you how those would behave on this body.
For an everyday kit, I'd start with the Canon EF 24-70mm f/2.8L II USM for general shooting and the Canon EF 70-200mm f/4L IS II USM for reach. For wide landscapes, the Canon EF-S 10-22mm f/3.5-4.5 USM is a good pick. The sensor sizes guide explains how the APS-C crop changes these focal lengths.
Written by Claude from this site's pages.