When Tyreek first began playing at WR, he was really just a speed guy, but over the last three years or so he's really come a long way in his route-running. Watched these recently, and just liked the breakdown on just how Tyreek has evolved as a route runner:
So here's a video discussing Tyreek in 2017, with Alex Smith as his QB. Notice how most of the time he's just using his speed and quickness to get open. However, you can also see that he's a quick learner, as evidenced by his two plays against Aquib Talib. If the first instance, Talib wins the battle by getting a really good punch on Tyreek, slowing him down and also completely disrupting the timing of the play. In the second instance, Tyreek uses his footwork to disrupt Talib's footwork and blows right by him.
https://youtu.be/TdD3fougXLA
Here is another breakdown of Tyreek that's a little more technical using examples from 2018:
https://youtu.be/9-t63nJ3bOg
Here's another one about Tyreek's route running and just how technical he's become; it's not just about speed anymore:
https://youtu.be/Rd2pREWLkvI
Anyway, if you like the more technical aspects of route-running, these videos are pretty informative and fun.