That being said being an immortal makes the game ultra boring in my opinion. All the difficulty is removed and I usually find myself ending up abandoning that game soon after.
That's what happened with the game I mentioned. It fired so early that I just gave up. Although, on the other hand, my favourite game I played was as an immortal satanist. But I was using the console to make a crazy story and give myself challenges, so that doesn't really count. Every little bit I'd give all my titles to one of my recent children, move myself to a different part of the world, and start again with a different goal in mind, but a hard time limit to complete that goal before I had to "flee" again. It was a lot of fun, played like that from the 700s start until the 1300s, then converted the game to EU4 with my immortal guy controlling a merchant republic. Never did finish the EU4 game though, that game is way too much of a slog to get through.
How do you that? Restart in a different part of the world I mean and give your titles to your children.
It sounds like a very interesting idea for immortals
Using the console. There's a lot of different commands that I used. But you can do anything from switching your character, to giving titles to whoever, to changing your culture/religion, to changing your government, etc. You can even set and remove specific character flags if you want to get really funky.
So what I would do is give myself a small county in wherever I'd like to go next, make that my capital, then just give all my titles to my child. Then switch to them, give me independence, switch back and be on my merry way. I'd usually swear fealty to somebody and go from there, unless I was trying to do something specific. I played as a satanist the whole time to, so I just kinda RP'd it through that in my head.