i have SE 2020 but i still dont have ios16 update?

No. That is not normal.

Did you participate in the beta program of iOS version 15? If YES, then you may still have the beta profile installed on your iPhone and that is preventing you from updating to iOS version 16. To check this, open Settings ➡️ General ➡️ VPN & Device Management ➡️ Configuration Profile: Here, if you see a beta profile installed, then tap on it and then choose remove the profile. Once this is done, then restart your iPhone and attempt to update your iPhone again.

Axel F.

If you have previously used a beta version of iOS, you will need to remove the beta profile.

How to uninstall iOS or iPadOS beta software - Apple Support