Still no. Withholding has absolutely nothing to do with whether or not you receive the tax credit and to what extent. Nothing.
An example:
You earned ~$80k in income, complete your form 1040, and your tax liability after deductions, etc. is calculated to be $8,000. This means you owe the government $8000. Now let's say you also bought an EV that was eligible for the full $7500 tax credit. Because you have at least $7500 of tax liability, the credit reduces that liability dollar for dollar, so you now owe the government $500 in taxes for the year.
Now let's say you had $4,000 in pre-payments withheld from your paycheck over the course of the year. Those credits are applied to your tax liability, meaning when you file your return you have $4000(prepayments) - $500 (tax liability) = $3500 refund.
The calculation remains the same regardless of the amount you had withheld from your check, whether it's $0 or $20,000. If you had $0 withheld, you would owe the government $500 to settle up. If you had $20,000 withheld, you would get a $19,500 refund.
One last time - the amount of pre-payments withheld from your paycheck via deductions has NOTHING to do with your eligibility for the tax credit.