Can you play a land during a turn you took an extra turn granted by Time Warp?

Time Warp (and similar spells) simply grant you an additional turn. That extra turn proceeds through all the normal phases and steps, including an untap step, upkeep, draw step, main phases, and end step. Nothing about the extra turn restricts or modifies your land-play ability.

Under CR 305.1, a player may play one land per turn during a main phase when the stack is empty, unless a rule or effect increases or decreases that number. An extra turn grants you a fresh instance of that once-per-turn permission — it doesn't carry over from the previous turn, nor is it taken away.

CR 500.1 confirms that a turn is a separate game object with its own set of phases. Each turn, including extra turns, resets per-turn permissions such as the land drop, so you're not using the same 'slot' from the turn before.

Concrete example: It's your turn and you play a land during your main phase, then cast Time Warp. On the extra turn you receive, you untap, draw, and during your main phase you may play another land — because that extra turn is a brand-new turn with its own land drop available.

The only exception would be if another effect specifically restricts land plays on extra turns (e.g., Teferi's Puzzle Box doesn't do this, but a hypothetical effect saying 'you can't play lands on extra turns' would). In a standard game with no such effects, your extra turn always includes a land drop.