i have had my brightness box unchecked for ever .. You can pinch the top left and brightness will go down. hold top right and brightness will go high.. i'll give that "LUX" thingy and see if i like it more..
I have the auto feature off and adjust the brightness manualy as I need. Usualy keep it at -30 when I dont use the phone and never go over +30. This seems to help as I mentioned previously. Also I use my phone a lot at night or inside and I rarely need to go over +10 cause that is bright enough for me. And as I mentioned I turn brightness down to -30 or more when I dont use the phone