If you efiled there should be an Electronic Postmark page. Probably near the end. That is your proof and signature. If you print out your return to give someone you will have to sign it in ink for them.
How to get or print a copy after filing
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-get-a-copy-of-a-return-i-filed-this-year-in-turbotax-online/01/25932