Each portfolio layout has a set size for the thumbnail images in column view. This is done to ensure the columns line up and are a consistent size. If you wish to change the default size, it can be done but requires a few edits. See the below example for the Portfolio 4 column layout, you can follow the same steps for the other columns, just make sure you are changing the right code for the column you want to change.
1. In includes/class-avada-init.php find the code below and change the size to your liking.
2. Then you need to change some CSS to match the width and height you used above. Copy and paste this CSS into the CSS tab in theme options.
3. Please also make sure to change the containers to the right size:
4. When you are finished, you need to use the Regenerate Thumbnails plugin.
Please note this is a customization that is outside of what we can provide for theme support. If you perform the customization, you will need to maintain the changes for future updates and also be able to troubleshoot any issues that arise. Thank you.