Azure move app service to a different app service plan

I would like to move App Service 3 which is into Resource group 2 but uses app service plan 1, to app service plan 2. Is this possible?

Based on my understanding App Service Plan 1 in the resource group 1 and Service Plan 2 in the resource group 2, we can't do that from azure portal currently. According to the official document, we could change service that in the same resource group and geographical location.

Only valid plans (in the same resource group and geographical location) are shown

About we could not create App service plan in the change service plan interface, and I also repro it. In my option,it is not a development issue, and we could report a ticket in the azure portal.

But we also could create a new App service plan in the same resource group (Resource Group 1) and geographical, then try to change the service plan, it will be shown in the change Service Plan interface.

In my option, it is not recommended that WebApp application and Service Plan are not in the same resource group.