More or less. You'll pay the full purchase price and that amount will factor into the monthly payment if you are financing. THEN, the next year when you do your taxes, they'll take $7,500 off whatever you owe in taxes or you'll get $7,500 back in addition whatever you were going to get back otherwise. At least, that's how it worked with the $1,750 I "got back" with the model 3 I bought at the end of 2019.
You won't get $7500 back unless you OWED at least $7500.
Where people get confused on this is the difference between tax liability and tax withholding.
You owe X dollars for the year to the IRS for taxes. That's your liability.
If you work, your employer will withhold some money to essentially "pre-pay" this.
When you do your taxes, you compare one number to the other and either the withholding overpaid your liability- and you get a refund of the difference...or it underpaid and you owe the difference.
The $7500 EV tax credit offsets LIABILITY. But only to the amount of that liability.
Removing the withholding part for a second- If you only have $3000 liability, you can't get $7500 in tax credit... you'd only get the $3000 liability offset and owe $0 and get $0 refund.
So the tax credit alters the liability number.
Then if you do withholding that'd be compared to the tax-credit-adjusted liability (which again can not be less than 0)- if your liability goes to 0 with the credit then your refund would be whatever amount your employer withheld.
That's why you only get $7500 "back" if you have at least $7500 in liability in the first place... and "how much you normally get for a refund" tells you nothing about that.