Full width designs

Hiya this is a pretty generic question but I'm having a hard time trying to figure this one out. Plenty of modern designs these days are full width, but then how do I go about with the break points? And how would I know the ideal sizing for space and fonts especially for larger devices? Like I've learnt to always put a max width but like in this example the image stretches to the extreme left. Is there any resources already out to help with this?