The 5G network was initially introduced in 2016 when the Xiaomi Mi Max Prime came into the market. 5G network starts deploying worldwide in 2019, so there is no logic to having a 5G network in Xiaomi Mi Max Prime.
No, there’s no chance to support 5G networks in this phone. Xiaomi Mi Max Prime supports a stable network up to 3G and a few Indian 4G bands that are not stable everywhere.