how to reduce ping / latency with 5g home internet

I am new to this service and still on my first day of use. When I do a speed test, the ping appear to be in the teens if I am using only one device. While one is doing a speed test and I start the same speed test on a second device, the ping time goes into the 300's and 400's. Speed is also variable going from a high of 250 up and about 90 down now, but I have seen 100 to 150 down and about 30 up during the daytime. Seem like this service is great for a single user. Might not be so great if a few people are connected and doing demanding stuff. Ok for watching videos.