Try this sudo pacman -S dkms-rtl8822cs.
I managed to get wifi working on my X96Max+ for earlier kernel, but not for latest/
==> Unable to install module rtl8822cs/2020.11.20 for kernel 5.14.10-1-MANJARO-ARM: Missing kernel modules tree.
look here https://forum.manjaro.org/t/manjaro-arm-on-amlogic-tv-box/34662/648?u=loop223