"Knowledge Panels" appear to the right of Google search results for people, organizations, etc. The information displayed in Knowledge Panels varies, based on the item searched. When searching for one's favorite local coffee spot, the Knowledge Panel may display useful details like hours of operation. Knowledge Panels related to people typically display a photo, mini-bio, and links to social media profiles. In 2018, Google established a verification process for authorized representatives to suggest edits to some (not all) of what appears in Knowledge Panels.
From performing Google searches on leading 2020 Presidential candidates, not all candidates and / or their respective campaigns have claimed the Knowledge Panels.
This assessment is based on seeing a "Claim this knowledge panel" link appearing below Knowledge Panels for some of the more covered candidates running for President.
As of July 10, 2019, the following campaigns and / or candidates do not appear to have claimed their listings:
Candidates not listed may or may not have claimed their Knowledge Panels.