Change alert tone for GMail incoming on Iphone11

IF you're referring to the gmail app and not the apple mail app, then you need to ask google or look at their support site, this isn't an iphone or Apple issue.

Checking on my phone notification for the gmail app, there is no settings to change the alert only to turn it on.

You cannot. I tried and went around all the options on the phone, in the sound settings within the "settings" on the phone, and also in the Gmail app itself.

They used to have the option to do so maybe less than a year ago, then the option is now missing. It used to be inside the Gmail app by pushing the 3 bars on the left, and go to settings and then there was an option for sounds.

There is no option to change the notification sound for the Gmail app. I'm guessing what people are referring to is the fact that you can change the alert sound for mail from your Gmail account that you receive in the Apple Mail app.

Personally, once InBox went away, I switched to an app called Spark. It doesn't give you a choice of notification sounds either but, I like the sound it does make.