Not sure if this can be done realtime (or in deployed and packaged game, tools are most probably editor only), but there are landscape editing blueprint tools, you need plugin for it.
So in theory you could make circle island landscape then modify those blueprints a bit. Add auto landscape material, then something to create auto foliage and you have procedural maps. This would make “poor man” procedural island. However i do not think this alone is enough for full game. There is no feedback, i think it will be very hard to make code that finds spots for things like villages, roads etc. For prototype would be more than enough.
This is that system showcase/tutorial:
