The two software transcoders I use are, Handbrake and MakeMKV. Of the two, MakeMKV does a really good job and it can tackle Blu-Ray too. Downside, the output files are rather large.
This is where Handbrake comes in. It can really slim down the bloated output from the forma to a more modest size. If you have enough disk capacity, you can skip Handbrake.
Finally, import into Jellyfin. To output to the family TV (not 4K), I'm using a modestly priced Roku streaming device that has a Jellyfin client and it does a pretty good job.
I believe, to achieve 4K you will need to transcode with a GPU.
Currently, I've around 520 movies and probably around a 1000 TV episodes on my Jellyfin server, all transcoded mainly from DVDs and some Blu-ray disks I've bought.