What Plex features, add-ons, extensions, etc. would you recommend taking advantage of for quality of life?

Been using Plex for years now. Wouldn't say I'm a "power user". No dedicated server, just run it from my personal computer. Only really use the basic features. Upload media files, subtitle files, and play on my TV.

But haven't really explored all of the features or extensions/add-ons that I've heard people talk about. Are there any that you'd almost universally recommend for quality of life improvement? Any that might be more niche but would still be worth checking out?