My 2020 has no scheduled transmission fluid changes in "normal" service. In "severe" service it's every 45,000 miles.
The fact is that for a 2018 Equinox used in normal service, as most likely are, the lack of a transmission fluid change is not an indication of negligence or carelessness. See page 371 and 373 of the 2018 Equinox Owners Manual: https://cdn.dealereprocess.org/cdn/servicemanuals/chevrolet/2018-equinox.pdf
OK, now this is where people can start posting their thoughts on "normal" versus "severe" service and how they change the transmission fluid three times in a row every 30,000 miles based on some experience they had back in the 1970's.
And they've never had a transmission problem. Statements like that are trying to prove a negative: "I did this and the bad thing never happened so it must be because of what I did" while ignoring that the "bad thing" may never have happened without that extra work.
The OP certainly could ask the dealer to see the inspection they performed on the car. If the transmission fluid was not at visually checked they could ask the dealer to do that as part of the sale.