Drawing synchronization between devices isn't available yet, but it is something we're working on. The problem we have to solve is, well... that amazing drawing you've done on your iPad Pro? Your iPhone's not going to have an easy time loading it. We're currently working on effective solutions to these kinds of problems.
In the meantime, you can transfer individual drawings between devices by exporting your sketches in CPT format. Save them to either Files or the Cloud of your choice, then import them as new drawings on your other devices.