Maybe it’s not THAT obvious, but it’s fairly simple as you’ll see.
You’re not going to use a Webflow image element, but a custom code component.
Your custom code component MUST be placed inside of a Collection list OR inside of a CMS Template Page.
Inside of your collection, you’ll add a URL field if you want to use the complete URL (ie: http://www.mysupercustomCDN/images/image.jpg) or, if most of the URL is predictable (doesn’t change), a text field. In the URL field you’ll put the complete address for the image (http://www.mysupercustomCDN/images/image.jpg), and on the text field, if you chose it, you’ll only put the name of the file (image.jpg).
Let’s consider you’re using the text field and add only the name of the image to the CMS items.
Drag a custom code component inside of the Collection List or Template Page.
Add an HTML code for an image
Select the part of the code that will change (the file name) and click on +Add field, then select your CMS field
Now you have a dynamic URL that will display your CDN image referenced in the CMS collection
You want to easily style this in Webflow? Add a class in the code.
Now drag any image in the Designer and add the class to it
Style it as desired and delete it. Your CDN image will be styled the same way.