One has to be smart about weaving in descriptions without having it as a block of text interrupting the flow of the narrative, especially in contemporary works. I suggest including body language and character actions to sneak in physical descriptions. For example.
"Hey," Kylie greeted, twirling a blonde lock around her fingers. Her blue eyes flitted to her classmate.
Vernon gifted her a smile, white teeth flashing against dark skin. "Hi." He jammed his hands bashfully into his windbreaker's pockets.
Same thing with explaining bold dialogue = spiritual being.
It could easily be woven in with Spice's first line. You know as the creator that Spice is a spiritual being, but a reader could think they're another kid. You could write it as:
"It's finally over!" celebrated Spice as they hovered over Adam and David. "Weekend, here we come!"
and then later on
"Pizza sounds good to me," he said, ignoring the rambunctious spirit.