Well loads of this is actually developing your own style to do it.
Like the transitions you mention from Afro he most of the time uses delay and echo effects that he syncs songs of different bpm to. Now other DJs accomplish the same by using loops or loop-rolls.
Then you can combine this with filter effects or solely use filtering and replacing beats by filtering out other beats.
Many of those topics are covered in our advanced courses and are quite a bit hard to explain in a forum, as you have to see them and then they need loads of practice.
The important thing with this is to “play around” do not try to do something but play with your arsenal. That is so much easier nowadays with controllers that can do all those things without having to invest in thousands of dollars of sampling and effects gear. Free your mind and just play with it.
.
