Several variables are available to drop a graphic into a Notification Template:

• {{ studio_logo }} - Includes your studio logo
• {{ organization_logo }} - Includes the Organization Logo uploaded to the Organization Details Tab

When dropping them into a template they are treated as text areas and are best included in a “Column” Box:

Click Add Content / Paragraph:

Using this container for the logo or image will ensure that it’s sizing stays within the container. There are also controls on the right for cell padding etc. to allow for more precise alignment.