How do I make a YouTube intro?

Or should you get one made?

The topic would be gaming suitable for Fortnite, Rainbow, GTA 5, Battlefield

You can do that in principle as you like. You can cut highlights from your videos and add music to them, do a kind of short text intro or whatever.

Tip: I would save myself long intros, everyone scripts after the second video at the latest. When I click on a video and I get dubstep at full volume, it closes faster than it started.

Blender - just animate an intro. It is a bit complicated for free. Or you can create a compilation with a video editing program with your best shots and edit the whole thing with effects as an example. Creativity is required.