Is there a way to equalize sound when making your own CDs from files (see details)

I have a friend who has several hundred CDs, perhaps low thousands, and has been collecting them for 40 years. He doesn’t do Spotify or Apple Music or anything—he likes supporting bands with purchase of physical media.

Anyway he and his wife (they’re my age—old) are going through the process of organizing all of them and figuring out what they want to keep and what they want to dump. The problem is that there are CDs where they only like maybe one or two songs.

What they want to do is create mixed CDs like mixed tapes with different files. The problem is that in many of the songs (mostly prog rock and classic rock) the volume difference and dynamic range are very different. So they’re constantly turning the volume up and down.

The question is, is there software where they can rip the CD files, and then create their own CDs but the software can equalize the volume in such a way where its relatively constant?

Now, I don’t know if there is an answer to this. The recording engineer of Caravan is a buddy of mine and I asked him and he didn’t know. But I figured I’d ask Fluther before giving up.