I can't seem to figure it out. It feels like I can only use all 3 features (SMS, calling, internet) for SIM1 or SIM2 but I can't mix them like I can in my Xiaomi Mi 9T.
For Calls , you can use either SIM1 or SIM2.
Go to Settings -> Network & internet -> SIM card
Under the section "Preferred SIM card"
Voice call -> Pick SIM1 , SIM2 or 'Always Ask'.
Data service Network -> pick SIM2 (if that is what you want).
And so on.