For the design of a mobile app or even a website, it is always good to have variety in terms of designs, icons and more, so that when you start with the graphic design of the app and its entire interface you have variety and can achieve a fairly optimal result.

Adobe xd is a site where I found a lot of variety in terms of layouts, templates, icons, illustrations, templates that offer a fairly good interface for users as they will feel familiar with them, whatever the app is, a mailbox, a store, social network, etc.

You can also see that you have adobe xd ios ui kit for mobile devices with ios operating system, also you can see the compatibility with some mobile models and their software!