Anmol S. sure so one way you could go about doing this is to duplicate the default container and keep the name with the "copy" in - go back to the default container class and rename it to a custom class name like:
container-custom (I know, how original)
And then go back to that class you duplicated with the "copy" in it and rename it back to the default.
Go back to your new container-custom class and start to make style modifications like removing the max-width and adding width 100%, etc.
So now you've effectively just propagated that new custom class across your entire project, while still following Client-First naming conventions and saved yourself a lot of headache.
Hopefully this makes sense but if not, happy to do a quick loom.