In an interview with Collider, Transformers: The Last Knight producer Lorenzo di Bonaventura spoke a little bit about the movie's story. Essentially he says it will dive deeper into Transformers mythology and is its own movie that is not specifically designed to set up future movies. Below are the key parts and most of it was already covered via the set visit articles (when this interview was conducted).
Question: What is the basic thing going on here?
...I think one of the great things that came out of [the writers room], was – one was sort of refreshing ourselves in the depth of the Transformers mythology, which is actually quite impressive, and two was building it out, and taking some things–sort of the way the movie ended, you’re going, all right, it’s headed in that direction. ...So I think–I know–you’re going to get two pieces of the mythology that converge at the end. So that’s sort of the driving part of it, of the movie, I would say.
So how much is it now that you guys are thinking this is the first of many future movies, and laying those Easter eggs? Do you know what I mean?
Yeah. You’ve got to be careful with that stuff, because then you start thinking about the other movies and not about the one you’re making. There’s definitely, I would say, we definitely spent some time going “How does this link up and where are these other things going to go?” So I think in their initial construction in the writer’s room, and the initial sort of thinking, we spent a lot of time on that, thinking about the interrelationship. Now, when we’re making the movie, we don’t think a lot about it, it’s just what is in the script is in the script.
Does this set things up [for the Bumblebee movie]?
...two or three things in this movie that really have a meaningful aspect in terms of it, and then there’s a bunch of little things. But we’re not making this movie to set up the other movies.