If you’re feeling extra creative, you can use Text Replacement. Go to Settings > General > Keyboard > Text Replacement.
There, you can create a shortcut. For example, type “lwn” and have it replace with “let’s go lowercase now” (all lowercase). It’s like a cheat code for your own language.
You could even set “im” to “i’m” with no capital. This is your keyboard, your rules. Be the architect of your own tiny universe.