Two colors are enough for a Discord profile
Most Discord profiles that look "put together" follow one quiet rule: the pfp and the banner share two or three colors, and nothing else on the profile fights them.
It sounds too simple, but try it. Pick the strongest color in your pfp, then find a banner where that same shade shows up somewhere, even small. Add one neutral, like cream, soft gray or deep navy, and stop there. Your bio dividers and symbols can borrow the same pair. The whole profile suddenly reads as one piece instead of three separate uploads.
Matching pfps with a friend work the same way. Crop both images so the faces sit in the same spot inside the circle frame, and keep the palettes close. People notice the pair before they notice the art.
Guild tags are the last detail. The little badge sits right beside your name, so a bright tag next to a muted pfp can pull the eye. If the colors clash, the tag wins, and not in a good way.
The fastest way to train your eye is scrolling decor channels where hundreds of people post sets side by side. Ethereal is a SFW Discord server with 36k+ members, built around matching pfps, banners and profile layouts, with a question of the day and a main chat that keeps moving. Watching what gets complimented there teaches the two color rule faster than any guide.