We each have a very unique idea of color and color sense. My purple and yellow would be a bolder, more graphic purple and yellow than someone who works with 30s fabrics.
If you can, I'd spend some time looking at fabric with DIL. One of my Tuesday group members is making a top for her DIL-equivalent and described the fabric colors to us. I responded that I had the perfect fabric -- which I did, a modern soft almost water color paisley but cerulean blue, purple, and silver as request. Only problem is that the lady making the quilt hated that fabric even though DIL agreed that was the color palette she wanted.
Sometimes I let the fabric guide me in what to make and design around a piece of yardage, other times I have to find something that fits what I want...
My first go-to place is equilter.com, they have a ton of free patterns many of which are based around panels and have options to buy the kits as well, but keep in mind that fabric is changed over so you can't get everything you see. But I'd look at fabrics first and see what inspires you and then maybe look at ways to use that fabric.
So, for me, I'd be picking a project more like this
https://www.equilter.com/pattern/112...w-poppy-spirit
then this
https://www.equilter.com/pattern/1120/peony-dance
But when I made a purple quilt top for my cousin (sigh, still not quilted), I went traditional Amish of all things...
Unfinished Quilt Stories