Hmmm
Geten seems to go just past Dabi's chin (made a guess with the hood on and adjusted a tiny bit cuz he looks to be slouching a little).
Dabi is canonically 5'9. Not very tall for a grown man. Kinda average.
Let's see what we can approximate as Geten's height then......
...
...
HM O^O
Conclusion:
Of course, this could be far from accurate, considering heights are pretty inconsistent in Heroaca lol. After all, Dabi and Shouto are supposedly the exact same height, yet Dabi is always drawn as if he's towering over him. Could argue it's an artistic choice to display a power dynamic, though it's a pretty common nitpick with official character heights and scales in the show/story not always matching, but I digress. Anyway the mental image of Geten as a tiny 5'2 gremlin is just too enticing.