This is called BIMI which stands for Brand Indicators for Message Identification.
From Litmus.com’s post:
BIMI is essentially a text file. That text file follows a specific format and lives on your sending servers.
When a message is delivered, the recipient’s email service looks up the BIMI text file—and where it’s hosted—to ensure that the message can be verified. Once verified, the BIMI file tells the email service where to find the sender’s logo and the email service pulls that logo into the inbox.
Please note: logo must be in SVG format and u need SPF, DKIM and DMARC authentication records already setup.
