Hi vinc112,
Yes you can resize image in VEC.
Steps to Resize:
1. Open site in VEC. Select Image that you want to be resized.
2. Click on Layout then resize
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3. Once you click on Resize option will appear to change the Width and Height:
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4. Click on right click to save the changes.
Reference document: https://experienceleague.adobe.com/docs/target/using/experiences/vec/viztarget-options.html?lang=en
Regards,
Akshat Jain