The Play Store description is the source we will keep quoting until it changes: Erangel comes pre-installed. You should not need another download before the first classic drop.
Other maps and modes are optional later. That is the whole point of LIGHT — you choose what extra storage to spend after you can already play.
Anyone listing Livik, Miramar, and ranked as “guaranteed on the home screen day one” without a Level Infinite patch note is guessing. We will update this guide when the in-game download list is public and stable.