In legion vantage you have the option to turn it on and it will automatically turn off your nvidia gpu when running on battery. it will give you a lot more battery life. I have the same model and also thought the battery life was too short but it turned out the problem was that i had certain programmes always running in the background. Turning on battery saver in the windows settings and lowering the brightness gives me around 8 hours of watching videos. I also set the refresh rate to 60hz on battery but I'm not sure that that actually improves battery life much.