I was googling around for wallpapers the other day, and I found a super old tweet from MKBHD sharing a Google Drive folder of free Wallpapers. There are some really great phone, desktop, 4k desktop, 5k desktop and even ultrawide desktop wallpapers.
To make them easier to browse through and download individually, I've organized them below. If you want to download the whole folder, you can find that here.
Desktop Desktop Wallpapers
4k & 5k Desktop Wallpapers
Ultrawide Desktop Wallpapers
Header image from Unsplash.