Okay, plugin number one is Imagine Board plugin, it is just recently updated and should work fine with Krita 5.3.x, if you need more information about that plugin, it has a very good wiki showcasing its abilities.
The other plugin may no longer work, but was so far my favorite for this task because it is a complete file manager as a plugin in Krita. If you give it a shot anyway is up to you. With it, you can adjust the preview sizes, the way the previews are shown and more or less anything a file manager can do, the plugin is BuliCommander, and you can read in the first post what it offers, but the version linked in the first post does no longer work, so you have to download the plugin out of this post of mine.
So far I have not tested it together with Krita 5.3 but because the most plugins (not all) work for me with Krita 5.3.0 the chance is high that it will too. But with Krita 6.0 it will no longer work, if I really begin then to try to fix this plugin from @Grum999 I can’t tell, because then I have to learn to code again, and that is something that I try to avoid for the last 3 decades right now (beside a little script juggling).
If you have further questions feel free to ask. But it is possible that I can not come to this topic back before tomorrow morning.
Michelist