Re-topology on photogrammetry scans

I want to retopologise some photogrammtery scans, but they all need to have the same poly count. Does anyone have any recommendations on how to do this quickly?

Would I be able to shrinkwrap an already retopolgised male body onto the scans?

Find a base model, make it fit the one in T-pose, and then just edit it to fit the other versions of the scan.
You can skin it fast to gain some time.

No need to create a retopology, you can find a base mesh, if I recall there are some on the blender website for free.

Just retopo the A-pose one, rig the clean model to pose it like the rest of the two. You can do further shape fitting afterward.