Yes you can save your return with another name to test in. You can have many copies. Go up to File-Save As or Duplicate on Mac. Give it a name like add TEST to it. Your returns end in .tax2023 and should be in your Documents in a Turbo Tax folder.
There is also a What-If worksheet you can play with. Go to Forms Mode, click Forms in the upper right (left for Mac). Then click Open Forms box in the top of the column on the left. Open the US listing of forms and towards the bottom find the What-if worksheet. Or you can copy your file with another name and test in the copy. Go to FILE-SAVE AS.
