First, In your Morphis Theme Options panel, under General Settings tab, include this code in the Custom CSS textarea:

#recent-works figure {
padding: 20px;

You can change the “20px” value to anything you like. Increasing the value will also make your images smaller.

Secondly, open portfolio.php file from the wp-content/themes/morphis/inc/ folder of the theme and search for three (3) instances of this line of code:

width="300" height="300"

And remove/delete them.