Problem increasing icon size on icon boxes

Hi,
I have checked the documentation and tried my hand at CSS before posting this, but I’ve had no luck.
I need to increase the size of icons next to icon boxes. I have been successful in doing so using code I found in an older thread:

/* Icon Size */
[data-av_icon]:before {
    font-size: 50px!important;
}
.iconbox_icon {
    margin-right:20px!important;
}

However, this also increases the size of the icons used for the search icon and burger menu in the header menu. How can I make this apply only to the icon box, please?