On iOS there’s nothing to install, it is just there in the display settings. Set it up for sundown to sunrise is my recommendation.
I am pretty sure Apple got the idea from the flu.x program which was there first. Apple was very smart to incorporate this feature into IOS. Us peasants that use PCs have to install it ourselves.
I don’t set flu.x on a timer. I adjust it as needed maybe 5 times per day. Takes me two seconds to adjust
So at sundown I have flu.x removing 80% of blue light but at 8PM I have it removing all blue light.