The closest you can get to re-usable components inside an Anim Graph, similar to functions/macros in Event Graphs is by using Linked Anim Graphs.
They allow you to move a portion of your Anim Instance to another Blueprint and then define variables and input poses. I’m using it to make repetitive structures re-usable.
As for other earlier replies: You can only make cached poses in the root of the Anim Graph, but you can use them anywhere. Not really sure why this limitation has been imposed.
Example:
