I recommend just skipping blame and going to git log -L to see the full evolution of a range of lines, I set up a little keybind in vim which does this for the current visual selection and it works much better than blame.
This feature is built into Emacs, no Magit needed. It's the vc-region-history command, bound to `C-x v h` by default. It works across all version control systems Emacs supports, not just git.
My config is kind of cluttered so this is a simplified version without dependencies. Glogr is for range history, GLogf for file history and <leader>gc for showing a commit based on hash:
https://magit.vc/manual/magit/Commands-for-Buffers-Visiting-...