Overwriting source assets with downloaded assets in an already built game

The info did not help.

You should consider using Addressables.

Hello,

Like Claytonious mentioned above, Addressables is the thing for you, please read up more them from this link as posted above.

Also as a starting point you can try to get a hands on experience following this Learn Course for Addressables

These should help you in starting out, best of luck!

Edit:
I’ve conversed with our developers and essentially the situation is as such .:
“You can’t just drag and drop a file into a folder and have it apply a patch.
Addressables content update workflow is for updating content within runtime.
I think what there looking for is the old school patch files. Which most don’t use anymore as most apps have some kind of manager before launching (think steam). e.g. Screenshots - NSIS