You would have to amend. Why didn't you get a Schedule SE? Did you fill out a schedule C for self employment income? You need a Net Profit on Schedule C to generate a sch SE. There are a few other things that go to Schedule SE. You don't normally add sch SE yourself. It is automatically filled out if needed.
Did you get a 1099Misc and enter it as other income but need to change it to schedule C income?
How to amend an Online return https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-turbotax-online-return/00/27577
