I'll just copy the answer from the (mostly) duplicate post to this one and remove the duplicate:
@ZeekTheGood said:
When i add a Collisionshape2D there is nothing to show that it is there. I have seen videos when they have a blue box and an orange outline to adjust it. But its not there for me. I don't know if it was an update or what .Ok so i was really dumb so when you make one if you can't see it look at the origin of the page (0,0) it should be there
@ZeekTheGood - in the future, please try to refrain from duplicate posting. If it is by accident, please let one of us in forum staff know and we'll remove the duplicate once possible. Finally, please try to use a descriptive title, as "CollisionShape2D" doesn't really explain the initial question very well and is very generic. I changed it for you to reflect the question, changed this discussion to a question, and marked this post as the answer.