Recently I was working with a customer that had completed a migration from Nintex for SharePoint 2016 to Office 365, and after migrating they realized that there was no longer the option to delegate the task to a new user with the out of the box task actions.
Solved! Go to Solution.
While there is no "in action" delegation option, you can update your workflow design to allow for this functionality. Here are two solutions to the delegation problem:
Designing Delegation (blog post): https://community.nintex.com/t5/Community-Blogs/Delegation-in-O365/ba-p/81148
Video Walkthrough (slightly different method): https://www.youtube.com/watch?v=73jessCaG6o