If you aren't looking to "extract" an avatar but rather want to to upload into Jira, several professional libraries offer Atlassian-style graphics:

Administrators often need to download all avatars when moving from one Jira instance to another.

: Jira typically saves custom avatars as 48x48 pixel images, though a smaller 16x16 version is also generated for use in comments. Bulk Downloading Avatars for Migration

Where can I find more project avatars? - Atlassian Community

In the world of project management, Jira avatars are essential visual cues that help identify users, projects, and issue types at a glance. Whether you need to migrate user data, personalize your workspace, or bulk-export assets, understanding how to download these images is key to maintaining a clear and professional Jira environment.

: Click on your avatar in the top right corner and select Profile .