How would I work with designs I’ve created in Sketch for iphone (375px) and then recreate them in Bootstrap Studio (BS4 edition)? This is what I’m trying to understand? I don’t know where I should start? XS which is still at 360px is still too small?
This is the only thing holding me back currently.
I would suggest redesigning your items to a larger size and let Bootstrap Studio manage the scaling down of them. That's typically what you would do for most things including images. At times you may need to make images in multiple sizes as well, same for some components that need to show different things on different sizes. The key is to not make your "items" to the smaller size or any specific smaller size, but to let the website code adjust the size for you. That's what responsive is all about. It's not a Bootstrap Studio issue at all, it's a user issue that is used to making things to specific sizing. :)
Providing I understood you correctly of course lol.