Battery Capacity iphone X

Is it ok for iphoneX's battery to plugin and play games? As games are using too much power and won't let it fully charge for hours. Would it effect the battery Capacity? Or should i charge it first and then play game?

2nd, how many times should i charge my phone in 24 hours? Only once or i can charge it two times as well and it won't effect battery capacity?

3rd, should i charge it when its less than 20% or should i keep it more than 30%-40% to keep battery capacity at max?