Yes 5G does drain your battery faster than 4G.
So if you run your 5G phone in 4G mode it will improve your battery. life.
I feel 5G is really more a marketing gimmick at the moment, (fomo) the technology needs to mature a lot before it becomes mainstream.
Most reviews I have seen say its basically "useless" at the present moment and in most cases performs worse than 4G due to lack of infrastructure.