You have to amend the constitution to enact term limits. It was passed by the Gingrich congress, signed into law by Bill Clinton, and knocked down by the SCOTUS.
My proposal is to end and an all post-office benefits for elected officials, including esp. pensions. Let them have an unmatched 401K plan nothing more. I think that would serve well as defacto term limits and no amendment required.
Interesting proposal. But their “pensions” would then come entirely from serving well heeled special interests who can provided the best sinecures after they leave office (i.e., sitting on boards, being paid advisors, receiving contracts as paybacks, etc).