Threads on the bolt would be easy fix , buy a new bolt .

However , I suspect it is a steel bolt into an aluminum head . So , I suspect it is the hole that is stripped .

You can try something like Blue Lock-Tite . Or even non hardening Permatex . J B Weld might work , but you would probably never get it out .

If it holds and does not leak , that is the most important thing .

If it does leak , then , probably the correct helicoil kit . With a new bolt , perhaps . Or perhaps , if you have room , drill & tap it the next oversize and use a new bolt .

God bless
Wyr