Tips on including more than two characters in your first five:

Create a trait that reader can latch onto. Maybe a character keeps pacing while others aren’t moving, or one w/green hair etc.

Don’t name a character if they aren’t important. Refer to them as title of what they do https://twitter.com/MelissaLaurenE/status/1313984746360369160

Establish a connection between main character and one of characters especially if they’re important to their story.

Try not to dive too deep into other character(s) so that the one close to MC can stand out.

Establish conflict between characters. If we know why there’s a disagreement in the group we can see where each stands
Start from one location and create movement in scene while also introducing characters. Instead of all at once in a location. School gym to library to band etc.

There is no one way to start your book. Being thoughtful about character introductions is key.

Go read the first Vanderbeekers. A sweet, heartfelt MG novel. I think there’s seven characters in the opening five pages. It can be done. With intention. And thoughtfully.