iOS 15 is available in my iPhone 7 Plus but download and install button is disabled even the phone is connected on wi-fi

Hello mukeshone.

Thanks for reaching out to Apple Support Communities. We see that you can't install iOS 15. We will be glad to assist. Your screenshot indicates that Airplane mode and Personal Hotspot are on. Let's go ahead and turn off Airplane mode and Personal Hotspot to see if that helps with the installation.

Go to Settings and tap Airplane Mode > Disable

Go to Settings > Cellular > Personal Hotspot or Settings > Personal Hotspot > Off

Next, try removing and redownloading the update: If your iPhone, iPad or iPod touch won’t update

"Remove and download the update again

If you still can't install the latest version of iOS or iPadOS, try downloading the update again:

1. Go to Settings > General > [Device name] Storage.
2. Find the update in the list of apps.
3. Tap the update, then tap Delete Update.
4. Go to Settings > General > Software Update and download the latest update.

If you don’t see the update in the list of apps or if the issue happens again, you need to update your device with your computer using Finder or iTunes."

Update your iPhone, iPad, or iPod touch

Cheers.

Hi mukeshone.

Glad to see that you are all set.

Take care.