Of course. But that is where the sophistication and training comes from.
The way this works is even different. It only takes a couple guys to kidnap someone and behead them. A team of 5 can setup a credible IED. It’s more about the supply chain than it is about working together as a team. In your OP they described how the lower end didn’t even know they were involved in a coordinated effort. There are a number of things I can think of that I could do if so inclined, by myself even. Look at what the Oklahoma City Bombers pulled off and there were only two of them.