What age is too old for a babysitter?

In the Netflix Original movie The Babysitter, the main character is a very innocent twelve year old Cole. His parents still leave him with a babysitter who, is one of the few people who actually treat Cole like his is more than just a kid. When his parents leave him for weekend trips, he begins to wonder, alongside his crush, what goes on after he goes to bed. On this instance, he doesn’t drink the pre bedtime shot of alcohol she gives him. This is our first indication that something seems to be wrong with this babysitter. She then puts him to bed and goes downstairs. Cole decides to wait for a while, then leaves his room to see what the babysitter's doing. It starts off with the babysitter playing truth or dare with some friends. This raises some suspicion but the thing that really caught my attention was that they had one person that didn’t seem to fit in with the rest of the group. The babysitter is dared to kiss everyone in the circle, when she gets to the person that doesn’t fit in, part way through the kiss, she pulls out two daggers and stabs them into his head. We start to see that the other ones that actually were part of this group actually fit in are part of a cult ritual. Then they say they need to get Cole’s blood, so he runs back into his room. One thing that was a struggle was the fact that Cole is afraid of needles, yet he manages to stay still while they take his blood. After the shock fades a little, Cole calls the police then tries to escape only to be stopped by the babysitter. The cops arrive as Cole is tied to a chair. The kids kill the cops, but in the process Cole gets away from the kids. They all come at him one at a time with the intent to kill Cole.
Through this situation, Cole is using his intelligence and level head to take out characters and using their flaws against them. The first one that dies is John, who chased Cole up the stairs before he escapes, and is then pushed over the railing and impaled by a trophy. The second to die was Sonya who was too overconfident and Cole used some supplies he picked up to shoot her with a firework and blow her up in the crawlspace. Then comes the weird one, Max, who notices that a bully is egging Cole’s house and tells him to go stand up to the bully. Right after he gets knocked to the ground, Max helps Cole up then gets back to trying to kill Cole. Cole get up in his treehouse and get rid of the ladder. Max, being a super athletic football star, climbs a rope. The floor breaks under Max and Cole and they both fall, but Max’s neck got caught in the rope and is hung from the rope. Cole goes back into the house and sees Allison who was shot in the encounter with the police. She is killed by the babysitter, Bee, who found a shotgun and wants to kill Cole. Cole escapes and goes to the house of his crush who calls the cops again, while Cole lays the works of a trap to get Bee. Cole takes the book involved in the ritual and threatens to burn it. He sets it on fire as Bee tries to put it out. Cole gets in his crush’s father’s car and drives it into his house to run over Bee. Throughout all of this killing and surviving, Cole gains a lot of confidence and changes from the scared boy who needed a babysitter to a boy who believed he could, from that point on, be on his own.