If it looks like a regular 120-volt outlet (versus something you'd plug an electric range or dryer into), then, no, you can't convert it to a large enough amperage circuit to run an conventional US electric oven and cooktop. That would require 8/3 or 6/3 and not the 14/2 or more likely 12/2 that there's now.
If you'd settle for a two-element insert cooktop with no oven:
https://www.amazon.com/Empava-Electric-Stove-Induction-Cooktop/dp/B07WKVQN1K/ref=sr_1_3
then you'd not need to change anything.
If one got creative? And taped the white conductors black on each end of the existing 12/2, powered them through a 20-amp double-pole breaker, put a NEMA 6-20R receptacle in that j-box? Then some lower-wattage four-element 240-volt cooktops could work.
If you also want an oven, it would probably be something out of Europe, really skinny with two cooktop elements and a very small oven (for game hens, not turkeys).