Splitting big Photos Library into smaller yearly libraries on Mac

If you edit your photos, the choice between Export Photos and Export Unmodified Originals is the choice between abandoning your originals or abandoning your edits. Only you can make that decision; some make decide they need to keep both.

If you have enough space, a way to keep both originals and edits is to clone your entire library, then carve the copy down to just specific years (2020-2022 in your example) by viewing Library in All Photos view sorted by capture date and removing items before 2020 and after 2022. Repeat for each set of years of interest with a fresh clone of the original library each time.

It should go without saying to proceed cautiously, delete photos only when you are sure you still have a copy, and keep good backups. (Yes, extra backups are appropriate when you are doing that much whittling.)

Those of us who use multiple Photos Libraries use the trusted 3rd party app PowerPhotos ($30) to help manage them. PowerPhotos makes copying picture and albums between Libraries, for instance, much easier-- it's the only way to copy pictures with their album structure. You can also do searches that include multiple libraries if you can't remember if that picture was from late 2022 or early 2023, for instance.

As markwmsn has said, don't do the export thing. It's good a an alternate archive backup, because it's good to have two kinds of backup, but you lose way too much, or you use way to much storage, for exported pictures to work.

His suggestion of duplicating and deleting is probably best, and it's the way that I, also, have divided Libraries.