Can I change the width or height of an element when clicked, with velo?

Velo is Javascript and to change the width and height would be more the CSS of the element that is currently a feature request. https://support.wix.com/en/article/editor-x-request-editing-your-sites-css-code-style-sheet

I was able to do something similar to what is sounds like you want to achieve with both hover and click interactions and using Velo as well .