In November last year, YouTube tested a feature within its mobile app that would allow users to communicate with others. However, at that time, it was only available in Ireland and Poland. The feature was expanded to some European countries in March, and now it has been further expanded to international markets including the United States, the United Kingdom, Brazil, and Singapore.
Not only can you send messages within the app, but through this feature you will also be able to share videos (regular-length videos, Shorts, and Live broadcasts). To use video sharing and messaging within the app, users must be 18 years old or above, signed into their YouTube channel, and have the latest YouTube app installed on their phone. This system will be available on Android phones as well as iPhones and iPads.
This messaging system includes a feature that allows you to delete a sent message by long pressing it and tapping "Unsend". Additionally, you can delete your own messages and block users as well.
Ref: gsmarena
