Grenades were primarily anti-infantry.
I don't know of grenades that could penetrate a tank's armor (speaking of a closed tank with hatches, not a troop carrier) in 1940-1953 that was issued to all troops. If you could get on top of a tank and open it's hatch and lob a grenade down, then that would be a way to stop it.
When you wanted to take out a full size tank, you brought along sapping charges, every country used these. They were very effective.
It's not loving Battlefield 1942.