Did you create the link as html code or from the Visual Composer? If is html code, then just add this attribute to the link: target="_blank" This will make the link open in new tab.
If you are using Visual Composer element then you have to use the element’s available options. If opening the link in new tab is not an option then there is nothing you can do. Unless you edit plugin’s files but this is not recommended because it will prevent you from taking future important plugin updates.
