Hey Lim,
I’m happy it was useful!
Different agencies tend to use either Figma or XD, in my experience Figma is growing in popularity. So you’re probably fine to stick with Figma, I also haven’t really used XD much. If you’re familiar already with Figma, I don’t think it’d take long to get comfortable in XD - they’re very similar.
If you’re purely interested in design, you probably don’t need to learn how to code, but I do think at least understanding the basics of html structure can help you be more mindful with your designs. From a job perspective, it’s a question that does come up quite regularly with potential clients so I expect employers do see it as a bonus too.