Question about signature effects

[NadaMucho]

I'm very comfortable making my own images using Paint.Net as I have my own little t-shirt side hustle. I'm wondering though, about the visual effects that are visible in some of the really cool sigs. Is it simple a matter of using an animated gif to display the effect? Also if someone has a special tool to perform the animations I'd be interested. I can do quite a bit with paint.net and Irfanview but if there's a quick and dirty way to add the effects that would be great.

Thank you!