I would like to perform a clean installation of MacOS Big Sur on my MacBook Air 2017. I've read two articles on how to do this, one said I don't need a USB installer, the other one said it is required. I just want to make sure before I do anything, do I need USB installer or is it possible to download Big Sur from the internet when performing clean installation?
Thank you.
Internet recovery is my first choice for reinstalling OS X. From time to time there are problems with internet recovery. Corrupt recovery partitions, firmware passwords, and a lot of misc hardware problems are what will usually prevent you from using internet recovery.
If you don't have another machine to write your USB installer, I would just make one to be safe. You could also run Apple Diagnostics before running internet recovery to make sure hardware won't be an issue. Out of hundreds of OS X installations I've done, I've only had a handful fail in a way that prevented me from using the original OS afterward, and in those cases it was always a major hardware issue.