I am developing Tabs using TabbedPage in xaml
. The default tabs Icons & Text size is big so I need to reduce the size of Icons & Text.
In my case I really wanted to skip all the custom renderers... and many of the implementations seemed much more work than should be necessary. I was also implementing Font Awesome Icons which seemed pretty straight forward, but all of the examples I found applied the icons to labels and nothing with tabbed page. After some dinking around I finally compiled this which works great and removes the need of a renderer.
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To answer the question of setting FontSize: Font Icon is a Font so it is set like any other. Example: