This is the doubt I also had when I upgraded from Windows 10 to Windows 11. But after upgrading to Windows 11 I didn’t lose any files or the data that is stored on my different drives. Upgrading to Windows 11 from Windows10 won’t make you lose any data unless it’s a clean installation.
But to be on the safer side, I copied all of my important data to my external hard drive so that incase if something goes wrong I can get the backup from my external hard drive.
After the upgrade, I didn’t lose any data including my bookmarks on Chrome as well as apps. And I was greeted with a brand new UI of Window 11 which looked much more beautiful when compared with Window 10.