its totally up to you which varients you choose to load. The theme doesn’t force any particular varient on any element.
So if you decide you’re only going to require regular (400) and bold (700) for a particular font then that just load them.
Bold is the odd one out – you can always choose Bold in the customizer – it uses the font-weight: bold; CSS property and lets the browser get on with it. But its a fake and never looks as good as if a bold (700) varient is available.