New in the encoding world , where to start?

[MeoLessi9]

Hello, long time ago I was immersed in video compression, I used software like MeGui, eac3to, mkvmerge, etc... But I've been disconnected for many years, and I would like to start compressing videos again, but I don't know where to start.
I have 20GB, 30GB, or larger files, and I would like to compress them with minimal loss of quality. In the past, I remember extracting the audio from the videos and compressing them separately with eac3to but I don't know if there are new methodologies? better ways to encode video. Is MeGui still used? What should I use to compress with the H.265 codec? What software should I download? .
For example, in a post I've seen the following:
"My current settings are;
10-bit. CRF 17. Slow preset.
selective-sao=2:no-strong-intra-smoothing:rskip=2:rskip-edge-threshold=3:aq-mode=3:aq-strength=1.2:deblock=-3:-3"

Where am I supposed to write those settings? What software is being used there?.

I hope you can help me and help me encode videos from scratch.

Thanks in advance for your responses.