How to create multiple flows in XD website for phone and tablet size plus a desktop web browser?

Hi @alexs6298960, I think considering web resolution (bigger than 1200px wide etc) and a mobile/phone (less than 768px width) is enough for the beginning. It's based on arranging a horizontal UI in a vertical way, when it comes to mobile, let's say you have 3 columns side by side, in mobile resolution those columns are going to be placed o top of each other, think it that way, and those numbers (1200 px and 767 etc) are based on Bootsrap's break points, you can see the whole list here: https://getbootstrap.com/docs/5.0/layout/breakpoints/#available-breakpoints which is a quite common standard, of course it can vary based on the design itself but it's about usually those numbers. Oh and this tutorial looks very useful: https://www.youtube.com/watch?v=Nxi2kBF7uiQ Hope this helps.

Yua can use 3 different size artboards in your project and share for preview. 

Also see August 2020 release of Adobe XD: Introducing Multiple Flows