You can get 4TB, although it’s a bit cumbersome: https://appleinsider.com/inside/icloud/tips/how-to-get-4-tb-...
Do you know if this works across shared drives too? Say one shares a 2tb plan with someone else; would both parties need the addition $10 “premier” plan to utilize 4tb?
On the other hand, I’d worry about this being getting patched and losing access. Seems like unintended behavior tbh