Can you use a land drop during your opponent's turn if you have an effect that grants additional land plays?

Playing a land is a special action defined in CR 305.1: a player may play a land on their turn, during their main phase, when the stack is empty and they have priority. Effects that grant additional land plays (e.g., 'You may play an additional land each turn') only increase the number of times you can exercise that action during your own turn — they do not change when you are allowed to take it.

CR 305.2 specifies the conditions under which a land can be played: it must be the player's own turn, it must be a main phase, and the stack must be empty. No additional-land-play effect overrides these timing restrictions unless it explicitly says so (for example, effects that say 'You may play lands as though it were your main phase' or grant flash to lands).

Only a card or effect that explicitly lets you play a land during another player's turn — or at any time — would change this. Standard additional-land effects like those from Exploration or Oracle of Mul Daya do not include such wording, so they simply grant extra plays within the normal window.

Concrete example: You control Exploration (which lets you play an additional land each turn). During your opponent's turn, you draw a Forest and want to play it. You cannot — Exploration only gives you a second land play on your own main phase. You must wait until your next turn to use either of your land plays.

If instead you controlled an effect that said 'You may play lands any time you could cast an instant,' that would be a different matter, but that is a very specific and rare effect, not a general additional-land-play grant.