Although it does cost a few quid, Litchi is your go-to for this.
Full planning on laptop/tablet/phone without being connected to the drone, and sync between all devices logged in so you are ready to fly.
It does a lot more than Waypoints, too.
There are other apps I’ve used too little to recommend.
Some “reading” on Litchi here, and do general searches for it, too.
This post confirms that it works on the SC.