With Method we've deliberately kept the avatar size small as it fits with the feel of the design. However you can easily upload a bigger avatar or custom logo if you wish.
To start click the 'Edit theme' icon on the top right of your logged in home page to open the edit side panel.
Under theme options look for the panel that says 'Custom logo' and upload your avatar/logo/photo as you wish.
The space for your custom logo is a maximum of 144px so make your avatar/logo no bigger than that.