I have created a new item template but have not found a way for the new item web edit button (blue plus icon) to use my custom template.
As you can see, I've created a new Tab item template as well as a branch template. The primary difference in this template is the Heading changed from a Rich Text field to Single-Line Text.
I created a new datasource configuration item to address the creation of tabs.
When adding a new tab, I see the SXA Tab Item rather than the custom one.