Dimples

Usualy, "Genesis 3 Male Head Morphs" and "200 Plus - Head & Face Morphs for Genesis 3 Male(s)" cover pretty much every basic head morph genesis 3 figure can have and need.
https://www.daz3d.com/genesis-3-male-head-morphs-22924
https://www.daz3d.com/200-plus-head-face-morphs-for-genesis-3-male-s

By looking at the description, i don't see the word "dimple" in the list of morph, but maybe the other cheek morph listed there can actually create such a thing. I don't know. (Never tried them.)

It's strange because the exact same product, but for the Genesis 2 generation, has a "dimple" cheek morph. Maybe it was an unfortunate oversight made by the artist when he/she created the Genesis 3 version of this product for that generation.

If that's the case....i'm afraid you are boned. Maybe...
You'll may have to resort to create a custom morph for you character by yourself.

Edit:

I forgot, you might also want to check "Genesis 3 Male Head Morph Resource Kit" and " Genesis 3 Male Head Morph Resource Kit 2 ".
https://www.daz3d.com/genesis-3-male-head-morph-resource-kit
https://www.daz3d.com/genesis-3-male-head-morph-resource-kit-2

They also have cheek morph that may do the trick.

On another note, while searching a bit, i did find a pack of morph over at renderosity that have a 'dimple" morph for G3, but alas, it is not available here.
"Head Morphs Resource Kit and Merchant Resource for Genesis 3 Males"
https://www.renderosity.com/mod/bcs/head-morphs-resource-kit-and-merchant-resource-for-genesis-3-males/114543/

Maybe you can find it somewhere else or ask if anyone here has it for share.