Please see the post Samādhi, Jhāna, and Sammā Samādhi.
“…But there are Paññāvimutta Arahants who had not cultivated jhāna but attained the Arahanthood in relatively short times. However, they also get to the fourth jhāna briefly at the moment of Arahant magga phala, but they need to practice jhāna to get into jhāna at will. …”
How is it possible to get to the fourth jhana if jhana is not cultivated?