Western animation/R

Ra

 * Rainbow Butterfly Unicorn Kitty: A preschool series about two kitties in a fantasy world.

Re

 * Ready, Jet Go! - SE2-EP04b: Jet, Sean, Sydney, and Sunspot shrank down to the size of mice, causing Mindy to become a para-giantess.
 * Regular Show: An absurd cartoon involving a extravagant group who work in a large park in extravagant adventures.

Ri

 * Rick and Morty: A science-fiction comedy series about the adventures of a mad scientist and his grandchild.

Ro

 * Rolie Polie Olie: Educational program for preschoolers where a child learns life lessons.

Ru

 * Rugrats: Children's series about the adventures of babies who use their imagination to interact with the real world.
 * Rupert - EP40:

Rw

 * RWBY: Jinn is a mini-giantess (roughly 12ft)