Two 4G sim enabled simultaneously (Jio & Airtel) - Samsung Galaxy On Max
What you are looking for is something like DSDV i.e. Dual SIM Dual VoLTE. Unfortunately, your smartphone does not support it and it will not be possible for Samsung to push an OTA update to enable it. 
The chipset itself is not capable of connecting both SIM cards to 4G networks at the same time. One has to fall-back to 3G/2G.