Yes. Either use the TurboTax desktop editions for 2018 to finish the tax return started with the online editions or use the IRS website for the free forms and schedules to complete the federal tax return manually.
See this TurboTax support FAQ for completing a 2018 tax return originally started using the online editions - https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-finish-a-prior-year-return-that-i-...
Go to this IRS website for free federal forms, schedules and instructions - https://apps.irs.gov/app/picklist/list/priorFormPublication.html
"Is desktop the only way to finish filing now......."
Yes, and for 2018 you need to buy the previous year's product (link below) if you do not already have the software. Further, you can only print and mail 2018 returns with TurboTax at this point; you cannot e-file them.
FYI ... if the SS# was issued after 10/15 then the EIC & CTC will not be allowed even if the program gives them to you ( there is no way to let the program know it was issued late) so the IRS will adjust your refund accordingly.
The Protecting Americans from Tax Hikes or PATH Act made several changes to the tax law, including preventing retroactive claims of the EITC and CTC by amending a return or filing an original return for any earlier year in which the individual or anyone listed on the return did not have a SSN valid for employment.
You can't claim EITC or CTC unless the Social Security number for you, your spouse (if married filing a joint return) or a qualifying child is issued before the due date of the return including any valid extensions.