Scrappy is as Scrappy does. I make many quilts with 2.5s. Some are "planned" scrappy meaning they may be all of one color family or in rainbow groupings AKA my avatar. It is your choice. My thought is if you are going random, go really random so all the colors and prints and just jumble together to create a overall look of playfulness with no color popping out as dominant. If you feel hesitant about diving into a bin of scraps of any size, combine them with a neutral. I have used white, cream, black, medium blue and even cheddar and purple as a neutral to soften the "scrappiness".
Slip over to the 2022 - 2.5 Birthday Swap thread here on the QB for more examples of scrappy. We love scrappy.