Pocket articles are displayed like Kepub, There is a patch, if Your are willing to patch Your Kobo, that
"Make KePub font sizes match ePub font sizes: ePubs render with # 1.5 times the font size of KePubs by default. With this enabled they match."
I Don't use that, if somebody uses it can give You more information about its usefulness. Anyway You have to enable the patch called "KePub stylesheet additions" and then, into the file libnickel.so.1.0.0.yaml (I don't know how to call it, sub patch?) enable the wanted style modification.
But patching is more difficult to explain than to do