Can I manually geotag pictures in Photos on a computer running Big Sur?

When Apple dropped iPhoto in favor of Photos several years ago, I opted to load iPhoto onto my desktop computer because Photos didn't have one feature that was critical to me: the ability to geotag manually any pictures that weren't geotagged automatically in the camera when they were taken. Using iPhoto rather than Photos has worked well for me since we purchased a new iMac with El Capitan several years ago. I also had put iPhoto on our MacBook Pro at the same time, although I don't actually use it on that computer.

I just found out, when we purchased a MacBook Air running Big Sur last week, that iPhoto isn't supported any longer because it was a 32-bit application. So I'm stuck with Photos now. What I'm wondering now is this: When we replace the iMac at sometime in the not-too-distant future, will I be able to geotag manually any photos that I scan into the computer from negatives? I have 24 years' worth of 35-mm negatives that I'm slowly getting scanned into the computer, as well as another dozen years' worth of digital photos that were taken with a camera that didn't automatically geotag photos. Will I be able to assign a location, either by using GPS coordinates or by dragging and dropping a pin on a map, to those un-geotagged pictures? Or will I have to purchase some third-party software that permits manual geotagging and then transfer tens of thousands of pictures into it and set up new keywords for each one of them?