Why doesn’t the ios 15 update show up on my phone?

It might take up to two days for the phones to receive the update. Make sure you're connecting over WiFi and that you're not using a VPN. Let us know if you have received the update.

Make sure your device is compatible with iOS 15. If it is, go to Settings>General>Software Update. Scroll to the bottom and choose Upgrade to iOS 15.

What phone do you have and what is the current iOS version?

Did you ever download a beta version? If so delete the profile and try again.