Css grid is just another (rather large) tool in the css toolbox. It has nothing to do with a framework like bootstrap as such which could of course use css grid if you needed to.
I believe css grid is still too early to use but if your site stats are modern browsers only then it’s worth a risk. If you are developing for a client then make sure the client is aware of browser support.
As I mentioned earlier css grid is another useful tool in the css toolbox but it does come with some complexity that will take a while to understand fully. It is very powerful but I don’t see that the run of the mill coder is really going to get to grips with it easily.
I also note that once you’ve built your site with grid it’s not so easy to go back and tweak something a few weeks later because you have to understand the way it’s been built first. It’s quite awkward to debug someone else’s grid unlike the general css properties or indeed flex box ( which is far simpler than grid). Maybe it will get easier the more I use it which has happened with flex.
My approach with things like flexbox and grid is that I will only use them if there is no simpler way to do something. Don’t use them unless you have identified a need for them. If you are not using the powerful layout mechanisms or behaviours of flexbox or grid then there is not much reason to use them (aside from the slight performance issues of flex and grid).
It may well be that in the future everyone just uses grid but I think it’s a bar set too high for some people.