Welcome to quilting! Many projects for learning quilting keep the first quilt sizes somewhat small, most likely so if you finish via machine quilting vs hand quilting, you are not struggling with a large quilt under your sewing machine.
"DogHouseMom"'s idea to add large borders would work just fine.
I finished a mystery quilt recently, and wanted to make it into a queen size bed quilt, although the actual size was about 48x32. I was going to have two different colors of somewhat large borders to provide interest, and got enough material. However, I scrapped that idea, and made a lap quilt instead, surrounding the mystery quilt with the same two colors of borders. One reason I had to change from a queen size to a lap size was that I have not machine quilted large quilts, and the lap size would give me good practice. It has turned out nicely. Our cat is napping peacefully on it as I send this message, so it must pass muster.
Good luck!! Let us know what you decide. Quilting is a continuous learning curve. This quilting board is the best.
If you want, I can perhaps send a photo, but I am all thumbs with that.