Filter a Profile to See a User’s Posts

When you visit someone’s profile, you can filter their profile feed to show just the posts that they added. You can filter your own profile, too. Select the Posts by This User filter to show only posts from the user whose profile you’re visiting, including when you visit your own. It’s a quick way to get to the information you’re most interested in. This feature is available in Lightning Experience.

The Posts by This User filter on a profile

Chatter REST API and Chatter in Apex support filtering profile feeds by the profile owner.