The Emoji size for emoji sent from the keyboard extension is set directly in the keyboard extension, and is separate from the size in the main app.
If you would like emojis sent from the keyboard extension to be larger or smaller:
- Open the keyboard extension
- Choose settings
- Choose a size
- There are different size settings for static and animated emoji
- Different devices show a given size in various ways. There's now way to know or control how the recipient sees your emoji, because it depends on the their screen size and resolution.