https://www.reddit.com/r/sonos/comments/1jo4kq9/new_sonos_app_update/?rdt=46210
 

This should answer your question. 
 

The latest app and firmware update will bring back Sonos playlist features to the mobile apps. But as mentioned in the linked article be aware that even after the update the feature will be rolled out in phases to all users. So just wait until you will find it available. 

Cause it’s still in beta and they haven’t released it to everyone. 

​@LuvSon0s, This is not true!

80.18.23 (Android)

80.18.25 (iOS)

Release date: 3/31/2025

In this update:

• Ability to create and edit Sonos playlists
  • Gradual rollout: This feature will be available to all users over time
• Bug fixes and improved performance
• Requires latest Player update - 84.1-63110 (or higher)

https://support.sonos.com/en-us/article/release-notes-sonos-app-updates

Note, however, that the ability is in a gradual rollout right now. Just downloading and applying this update doesn’t guaranty access….yet. I suspect Sonos is making sure there are no significant issues before they open this up to all.