I've beaten night 6 so here's what i learned:
to unlock all sex scenes you need to die to each animatronic - Bonnie, Chica, Freddy, and Foxy. To get their 2nd scene you need to beat night 5, which is pretty straight forward, you just try a few times and you can learn
but if you're a noob you can try my strategy for night 6, although I'm not sure it will work due to Freddy being a total mystery to me (she killed me in earlier nights but basically did nothing on the 6th). There are 2 secret scenes I found also, one is the donut which you can get by just clicking the donut in your office a few times, and the other is Golden Freddy which you can get by selecting 6969 on the 7th night (unlocked afer beating 6th night)
my strategy to beat night 6 is fully based on saving power, this is because Foxy is a bitch. First things first I made sure to use the cameras as little as possible, at the start of the night I immediately put the camera on foxy's and then just close it for a while, then I would check here and there to see if Foxy's missing, if she is I rover the mouse over the left door button and only click immediately after hearing a running sound, then Foxy will thump the door 3 times (I think?) after which she'll leave, you need to wait half a second after the thumping stops or she'll enter anyway.
as to bonnie and chica it is as simple as listening for a slow thumping, this means that one of them got into a door, bonnie does this much more frequently so i just immediately closed the left door the first time the sound happens in the night, although i checked anyway to see if RNGesus hated me, so maybe try just doing a quick double click on the light to see if she's there, if she's not then directly close the right door, that's what i did for most of the night. After a door is closed i double click the lights consecutively to see if they're gone, chica is quick to go so she may be gone in the first or second check but bonnie takes way longer
there is no strategy i found to beat freddy, she just never appears, but in my winning run i had more than 10% at 5am so i left the right door closed and focused on the left, my power ran out but with a bit of luck i passed, i'm not sure this is needed, if you don't leave the door closed you could maybe not encounter freddy at all. Anyways use this as you will, good luck