Your habits die hard, coming from android, I feel you.
Try Google keyboard for typing, it works. iMessage is great if everyone is on apple train. If not, switch to WApp, Signal.. and use iMessage with Apple users.
Customization? After everything I don’t need all those options and features of android customizations. Just let it be simple. Sort your apps in bundles and that’s it. No more swiping of 5 screens to find it. Or use Siri to open it. Yes, Google is superior than Siri but it can do marvelous things sometimes:)
Try Shortcuts. Learn or copy some from someone and it could make some stuff easier for you.
There is vast amounts of stuff to discover and learn, just give it time.
Enjoy it and don’t stress yourself about it, adapt and progress, that’s all.
As for myself I will never go back to Android? Let’s just say “updates” and I think you’ll understand.