Favicon
The sizes generated for your favicon, the small icon shown in the browser tab and used when a shopper bookmarks your store or adds it to their phone's home screen.
The favicon itself is uploaded under Store Identity > Logo & favicon. These settings control the versions generated from it.
How to Configure Favicon Sizes
Select the store you would like to update
Click on Manage Store Settings underneath Settings
Open Image Sizes
Open the Favicon section
Set the sizes you want generated
Save your changes