I've managed to do that a bit in a few orgs, by slowly introducing typescript in a code base (and showing that it can be introduced progressively without disrupting too much) to then show how those files have become easier to work with. I guess that's the guerilla style of tech evangelism
The problem is, it's not always possible (if managers refuse to let you do it in the first place) or practical (if you don't get given the time or if you're working with a complicated legacy setup and can't make those kind of changes).
The problem is people can only really see the benefit by working with it for a while, but to work with it there needs to be some initial work to introduce it.