There are some things that are important to the story:

Severus, Dumbledore, and Fred are still alive. Plus maybe a couple other characters.

Percy and Harry know each other

Blaise is now the biggest bully, Draco admitted that he only acted that way because of his father

This will not include references to Trials of Apollo but Calypso and Leo have returned to camp and Nico and Will are dating

Draco, Hermione, Luna, Severus, and Neville are Demigods

Draco: Son of Athena-looks like usual but his hair is messy , he's more muscular, and he's smiling

Hermione: Daughter of Athena- looks like usual but her hair is a golden-brown color, she has gray eyes, and she's more muscular

Neville: Son of Demeter- looks like usual but more muscular

Severus: Son of Hecate-looks like usual but hair is not greasy

Luna: Daughter of Iris- hair is longer and is more muscular

Other things will be revealed in the book