How to increase image size?

To increase the image size in Divi Resto Menu add the following CSS code in Divi Theme Option.

.el-drm-layout-1 .el-drm-menu-item-thumbnail {
    width: 200px;
    margin: auto;
}

.el-drm-layout-1 .el-drm-menu-item-thumbnail img {
 width: 200px;
 max-width: 100%;
}

Note: You can change the width value as per your design requirement.

For layout 2 replace the layout-1 with layout-2 in CSS.

Output: