Not everyone has all of the possible six schedules that could have been part of your 2018 tax return. If you do not have a Schedule 3 it is because you did not enter any data that required it. Your 2018 tax return will print out with all of the forms and schedules that YOU needed in order to file your 2018 tax return.
But if you want to see what Schedule 3 looks like:
If you were being claimed as someone else's dependent then you could not take the education credit (line 50 of the Schedule 3) on your own tax return. It would have belonged on the return of the person who claimed you as a dependent.
Above line 31 it says Lifetime Learning Credit and Line 31 says " Adjusted qualified expenses (see instructions) Include the total amount from all Parts III, Line 31 on Part II, Line 10 " but I don't have any other pages after that.
I downloaded this previous return from my account on TurboTax so hopefully my file isn't cut off within the server or something.