CAHAYA Concert Ukulele Kit Beginner Starter 23 Inch with Gig Bag, Rainbow Strap, Fretboard Stickers, for Both Adults and Kids, Sapele, Model CY0070

Regardless of the effect of your height on size, the difference in Uke size is only 2.4 IN.

Both are suitable for singing, fingerstyle.

21 Inch: Small and cute, suitable for people who prefer playing and singing.

23 Inch: Medium size, good fingerstyle, playing and singing, more suitable as an entry one.