You can add keyboards for writing or using next to a keyboard to a new place in the list, then tap Done.
If you add a keyboard for a different language, the corresponding language is automatically added to the Preferred Language Order list. You can view this list and add languages directly to it in Settings > General > Language & Region. You can also reorder the list to change how apps and websites display text.
While typing text, touch and hold > General > Keyboard > Keyboards.
Tap a language at the top of the screen, then select an alternative layout from the list.