Julius Randle cannot be traded because ~6 months (slightly shorter this year) have not passed since he was signed to an extension. He will be eligible to be traded after Feb 3, 2022.
Jarrett Culver currently has a team option for the Grizzlies this season. The Grizzlies may decide to decline their option which would make him an unrestricted free agent. You may accept or decline this option, by default it will be accepted. You may also update his contract to perform actions such as a Sign & Trade.