Why can't I root my phone?

1.Enable Developer Option (settings - about phone - Software information - Tap 7 times on build number to activate developer option in settings menu)
2.Enable OEM Unlock from developer option (Currently no workaround for those who doesn't have this option )
3.Download TWRP for S9 or S9+
4.Switch Off device
5.Press Vol down + Bixby + Power to reboot to download mode, press volume up when asked to continue to download mode
6.Download Odin and open it, Disable 'Auto reboot' from option menu of Odin
7.Select TWRP (tar image) with AP tab of Odin and Start
8.Once Successfully flashed, you will see 'Passed' in Odin tab
9.Disconnect device and hold Vol down + power till screen goes off, Now immediately press Vol Up + Bixby + Power to reboot to TWRP
10.Select to allow modification
11.From TWRP, Select WIPE menu - Then FORMAT DATA - You need to type 'yes' to perform wipe. WARNING : This will erase all data including Int SD storage from device
12.Once format device completes, go back and select REBOOT' Menu and then - 'RECOVERY', This will reboot to TWRP again
13.Flash no-verity-opt-encrypt-samsung-1.0 and then Magisk
14.Once flash successfully finish, Reboot to System
15.Open settings - Developer option - Look for OEM Unlock option. It will automaticaly change to unticked after some reboot don't stress it's normal.
16.MAKE A BACKUP IN CASE OF BOOTLOADER RELOCK.

this is procedure for magisk root

anything else search forum or google