How to erase a disabled iPhone8+

I have an iphone8 which is disabled due to forgetting the entry password. I also want to return it to factory settings.

I tried the Apple instructions via iTunes, but nothing appeared (iTunes on an MacBook running High Sierra). This seemed to return the phone to Recovery Mode.

I then tried the Apple instructions using iCloud. This allowed me to attempt to use Erase my iPhone. I tried this, but then got 'Erase Pending', and 'This iPhone will be erased when it connects to the internet".

But how can this iPhone connect to the internet? It is currently disabled and says try again in 8 mins. But I won't be able to open it without a password, and no way of getting it on the internet.

I just don't understand where I have got to with my attempt to return it to Factory Settings.

WiFi is available, I have a working MacBook Air and iPhone 12, both connected to the Wifi.

It is now showing the Enter Passcode screen and Touch ID won't work either.

I would be really grateful for advice.