If you are using the standard deduction in your return instead of itemized deductions, TurboTax should allow you the $300 cash charitable donation to use with the standard deduction, but no more. 

You should be able to view the $300 cash charitable deduction on  your return.

Possibly but are giving was $7100, so how do I take it out of standard deduction to see if it would change anything?

The best way to enter is doing the following.

1. After logging into Turbo Tax go to federal >deductions and credits>
2. Scroll to the bottom of the screen and select wrap up tax breaks
3. Continue through until you reach a screen that says Based on what you just told us, the Standard Deduction is best for you. Continue
4. Next screen will say Charitable Cash Contributions under Cares Act. Here you can enter an amount up to $300.