You cannot transcode your offline media to higher resolution media. You will need access to the original camera files before you can do anything.
As Shane said…your options are then to:
1 Reimport in Avid at highrrs, if the footage was imported in Avid at low res originally. (Highly doubtful in today’s workflows…but not unheard of)
2 duplicate your sequence and try relinking it to a bin filled with camera originals. (Search for relinking sequence to all selected clips in open bins)
3 send a list to resolve, and relink there to the camera originals.
It does depend on where the originals were made to a certain degree, however if they were done correctly in Resolve in the first place, you should be able to relink them in Avid directly, if you are doing colour and online in Avid. I actually typically do the relink in Avid, even if I’m sending to resolve, so my list is already pointing to cam originals when it comes into resolve.
If the camera originals don’t exist, then you are screwed either way.