The facts will come out in time. The truth may be more elusive.
The people involved seemed to have varying ideas of what was expected of them, but some were obviously there to generally bum rush the Capitol for whatever reason. The timing wasn’t accidental though. The coup minded people involved understood, after twice foretelling fraud, and generally pressing every constitutional limit to raw power, that the legal proceedings of January 6th were a possible last ditch mechanism whereby they could steal the election.
Yes, it could have been a coup, if it had worked as some wished it to have. Who wished it had? Oh, to know the hearts of men. We can all have our theories about what Trump thought and when, but he has worked his whole life to prevent that kind of understanding.
But to indulge you, I will say I do believe it. I believe his lived experience taught him to be enough of a cynic and that he thought it was a possible. I expect the more logical part of his mind knew that pretending to prepare to stage a coup would play well with his base, bring in donations, ruin Biden’s day, and give him just enough cover to hopefully not be tried for treason, at worst, and just maybe actually deliver him another term, at best.