I want to be able to type in a date in one cell, and then automatically have the date that is seven days from the date I typed appear in another cell in that same row under a different column. How do I do this?
You can use this formula.
=ARRAYFORMULA(IF(ISBLANK(A2:A),"",A2:A + 7))
I've created an example file for you: new date from entered date