Can I correct an incorrect standard deduction? Filed jointly with 1 additional dependent. TurboTax shows only $30,750 not $33,850.

Your standard deduction is not affected by claiming a dependent, although you might get certain other credit(s) for claiming a dependent.

It sounds like you are filing a joint return and one spouse is 65 or older if your standard deduction is $30,750.

The standard deduction makes some of your income “tax free.”  It is not a refund.  You will see your standard or itemized deduction amount on line 12 of your 2024 Form 1040.

2024 STANDARD DEDUCTION AMOUNTS

SINGLE $14,600    (65 or older/legally blind + $1950)

MARRIED FILING SEPARATELY            $14,600    (65 or older/legally blind + $1550)

MARRIED FILING JOINTLY $29,200    (65 or older/legally blind + $1550)

HEAD OF HOUSEHOLD $21,900    (65 or older/legally blind + $1950)

@volt-1948   Where are you getting the 33,850 or the extra $3,100 to make 33,850?  That  isn't even the 2025 standard deduction amount.  

You can't change the numbers generated by the program that are set by the government. If you are able to override any amounts, that voids the accuracy guarantee.