Wish to separate Plex from my gaming rig... need advice.

I know this is a recurring topic, I’ve done searches and found many posts on this subject but most are from 2019 or older and I’m sure the answer then is not the same as the answer now.

Budget & power consumption are of primary concern… I’ve seen Dell Optiplex as a common recommendation as well as Beelink EQ13 (though I’ve never used Linux command line only versions with GUI so setup may be tricky.

I have 3x 20TB HDD with my movies/shows on them I would like to use so I’m trying to figure out the easiest method to switch to a low power consumption Plex or Jellyfin rig (though I’ve never used JF either)… I assume this would require a NAS because USB connectivity would not be optimal.

I’ve read a great deal about Intel CPUs with Quicksync handling transcoding as an alternative to a dedicated graphics card but nearly everyone talks of H264 transcoding, many of my movies are H265 to save space… Can this be achieved as well?

If you respond, explain it to me like you would a 5th grader please don’t make assumptions that’s usually where I get lost haha.

Thanks for your time!