Retrieving Full sized images stored in a Image type column in a dataverse table through Azure API Management

Question

We are storing images in a dataverse table under the Image type column When trying to retrieve it using an OData call through API management it only returns the image at icon size(144x144).

I have tried to use [Organization URI]/api/data/v9.1/accounts(C0864F1C-0B71-E911-8196-000D3A6D09B3)/myentityimage/$value?size=full but the clients are not authenticated to the backend so while it works in testing it wont work in a production environment.

We build up our OData query using FetchXML. It gives us the option to select the image which returns it in BASE64 but only as a icon(144x144).

Is there any way using this method to return the full image. I cannot find how to append the Size=Full

FetchXML we are using.

<fetch>
<entity name="[Entity Name]">
<attribute name="bt_attachment" />
</entity>
</fetch>

OData query that it generates.

https://[Organization URI].crm4.dynamics.com/api/data/v9.2/[Table Name]?$select=bt_attachment

The image column is the only one return.