Form 709 is not part of an income tax return. It has nothing to do with your Form 1040. It is a completely separate form that you can only file by mail.
Gifts given to family members, friends or other individuals are not deductible. Gifts received are not taxable to the person who received the gift, and are not entered on a tax return.
If your gift exceeds the yearly limit ($18,000 per individual) imposed by the gift tax rules, then you will need to complete a Form 709 gift tax form and send it to the IRS, although it is very unlikely that you will owe any tax.
TurboTax does not support Form 709. It is not an income tax form and would not be included as part of an income tax return.
Here is a link to the form:
https://www.irs.gov/pub/irs-pdf/f709.pdf
https://turbotax.intuit.com/tax-tips/estates/the-gift-tax-made-simple/L5tGWVC8N
Here's a link for Form 709 preparation software:
https://www.puritas-springs.com/product-category/federal
Here are some useful videos on the Form:
https://www.youtube.com/watch?v=a5wJow5h-No
https://www.youtube.com/watch?v=5Z_28sVOrTY