Follows and blocks (and lists and bookmarks) are the easiest to back up, you can download them as "CSV" files which you can import into any other account.
They're covered in steps 5 and 6 on the transfer guide:
https://fedi.tips/transferring-your-mastodon-account-to-another-server/
You can just do those steps in isolation, you don't need to do any other steps if you just want to back those things up or transfer them elsewhere.