iOS doesn't have a function to change keymap (as of Oct, 2019). But Apple allows us to change keymap within app. These keymapping is used for many app, like Blink. Wazari uses this too. Within the app if wazari keys are enabled, you can remap all modifiers.
Note: Capslock is turned on in OS level, therefore, when capslock is on, you need to turn off outside of this app.