Full ATP requirements, but not the actual certificate. From: https://www.delta.com/us/en/careers/pilots/hiring-faqs

At least 23 years of age.
FAA Commercial Pilot Certificate with Instrument - Airplane.
Current FAA First Class Medical Certificate.
All aeronautical experience requirements for an ATP, Airplane category rating, as set forth in 14 CFR §61.159.
Current ATP written exam.
Minimum of 1,500 hours of total documented flight time.

Note the Commercial Pilot Certificate. A candidate doesn't actually even have to hold a restricted ATP.