There are many words for small: little, minuscule, slight, tiny, teensy, etc., but in the world of cute animals one word reigns supreme: smol.
Smol is similar to small, save that smol things are adorable and you just want to squish them with love and kisses.
Smol is when you can't keep your voice from rising an octave and you don't care who sees you freak out at how cute something is.