One thing that UX designers love and hate is the use of external links. The traditional blue-colored and underlined text style often makes it stand out oddly in your interface and that’s when you would try different ways to beautify them or sometimes in the process just make it simple black text. But that creates a problem for the user.
Now they no longer know what is clickable and what is not. This is one example of lacking consistency in your interface design. If a link no longer stands out in the crowd, then it is no different from other texts.
There are a lots of ways to make the link obvious to users, color it, underline it, adding some hovering effect explaining what the link would lead to. Whatever style treatment you choose, NEVER use it on anything else that is not a link. Remember the principle of consistency.
I hope this was helpful.