My earlier post is the entire tag system for vanilla Strive, there are no other tags. There is no system for automatically replacing NPC art, though you could probably mod the gallery.gd file to use other images. Any slave can have its images replaced manually, so once you acquire an NPC you can replace their images, though that won't effect the quest images.
If you are looking for further tag support, then you will need to explore the improved random portraits mod (https://itch.io/t/281535/improved-random-portraits-v10). It still has some flaws as articulated in the last few comments, but works fairly well. It has a guide included in its files.