How to add a Quick Settings Menu tile for Automate (Android) - Example with a Flow that toggles the Font Size

First make sure you edit your Quick Settings Menu. Add one of the "Automate unused" tiles to your menu.

Here you can see that I have it added, but it is not being used yet.

Note: please excuse the subtitle "Size: 1.0". Normally it would say "Automate", but I am already using it, and I don't feel like removing it for the sake of this screenshot.

Now you need to add the block "Quick settings tile show" into your flow. Once the flow reaches this block, the "Unused tile" from before will be filled with whatever you select in the settings of this block (example next picture).

This is the settings menu of the "Quick settings tile" block. You can see the result of my settings here in the next image.

This is what it looks like when the button is INACTIVE.

This is what it looks like when the button is ACTIVE.