SiriusB
Hi
It is not possible as icon since this is border class css used for all the menu item and worked same. You can customize the part via css only here is example view i checked and created for using different css caret color
.t4-megamenu.animate.slide .dropdown .cs .item-caret {
border-top-color: #2bae35!important;
}
.t4-megamenu.animate.slide .dropdown .cs .item-caret a.active {
border-top-color: #2bae35!important;
}
cs is custom class you need to add in the Menu item options as link class
here is example u can set the icon via css using font code
.t4-megamenu.animate.slide .dropdown .cs .item-caret:before {content: "\f09a";font-family: 'Font Awesome 5 Brands'; font-weight: 400;}
Know more about using font via css here