I’ve invoked a number of times, and while possession isn’t guaranteed, it’s the first step. There are magicians who even claim that invocation is considered partial possession because you’re allowing them inside of you. I myself have been possessed during invocation, as have a number of people on this forum.
I’m just gonna leave these here, since you are clearly uneducated on the subject.
#Outlearned
There are a number of tutorials on this forum. Use the search function.