Manual You Can Update your IOS 13.6 Without PC.
1,Turn on the Device
2, Start at your Home screen
3,Tap Settings connect your iPhone with Wi-Fi
4,Your Battery will be more then 50%
5, Tap Settings >General > Software Update.
6, and then you find "download and install"(4.2GB)
7,click on "download and install"
8, you find "Terms and Conditions" click on Agree > Downloading will be start
9,downloading will be complete in few minutes
10,your device will restart
11,software will install wait few minutes and you get your device ready
Note, if icloud is ON in your device so you must have password
