Most introductory classes on astronomy start with an overview of the universe. How big is it? What is our place in it? Here are a few links to videos and resources to help.
(You can also search for the category “Astronomy” to find additional posts about astronomy in general.)
“VFX Artist Reveals the True Scale of the Universe”
I really like this size comparison of planets, stars, etc. It’s well done, and keeping the scale the same throughout gives a much better feel for the actual size differences than the videos in which the scale changes.