Add CSC to US unlocked firmware SM-G988U1

[Paauul]

I have a US unlocked S20 Ultra 5G (SM-G988U1), but I'm using it in the EU.

I'm missing certain features such as VoLTE, and think it has something do to with the CSC being XAA/XAA/XAA/XAA.

I would need the EUX multi-CSC firmware, but that only exists for the SM-G988B (international, exynos)

Is it possible to add missing CSCs to the U1 (snapdragon) firmware. Specifically EUX, ATO?