Hi there,
Most of that site is built using page builders – I’m not seeing much GP at all. For example, the navigation/mobile navigation is Quadmenu, the content is Beaver Builder, the footer is UABB etc.. You would need to check with those developers to see if the breakpoint can be changed.
As for GP, it’s possible to change the breakpoint for the mobile navigation/mobile header, but there aren’t any options for the content as of right now. Of course, custom CSS can fix most things.