If size is a large part of your sales pitch you need to show an image with some reference in it.

https://www.noypigeeks.com/android/unihertz-jelly-star/

While hands come in different sizes the picture there gives an immediate feel for the product. Next you might feel you want one. 95.1 × 49.6 × 18.7 mm is more accurate but there is no feeling.