AIUI, old cars are usually grandfathered in to these laws based on the model year. So cars manufactured before 1965 don't have to be retrofitted with seatbelts. And your Model T doesn't have to meet modern emission standards.
On emissions, a quick google gives me this:
> most states provide some type of exemption specific to older cars.
https://www.hagerty.com/media/archived/emissions-and-your-co...
But classic cars are not a big interest of mine so I don't know the details.