Is there a 72 hour change of mind when leasing a car in Indiana?

Probably not.

For reasons that aren't entirely clear to me, a lot of people think there's an automatic 3-day "grace period" on car purchases. This is NOT true for new cars in ANY state.

Some states do have laws that require used car sales to have a right of recission period.

Some states have laws requiring dealers to offer buyers the option to purchase a recission period in some cases.

There's no law that says a dealer can't put a clause allowing a recission period in the contract if they want to do so, or can't offer the option to purchase one even if the law doesn't specifically require them to. But this is up to the individual dealer.

If you've already leased the car, check the contract. It should state in unambiguous terms whether or not there's a recission period and if so how long it is. If there is one, it should also detail the terms: you may be required to pay a prorated amount and possibly also a penalty of some kind or another.

If you haven't leased it yet, ask the dealer. If he says there is one, get him to put it in writing in the contract.

Otherwise, you should plan on the answer being "no."