Making a ‘Band Page’

You need a Theme not a plugin to effect the appearance.
Since that is not running wordpress you will just need to go through:
https://www.ads-software.com/extend/themes/
and see if one catches your eye.
To keep a page from the menu, change the visibility (Upper right when editing a page) to Private or Password Protected.

I already have a theme I am using.
But only for specific pages I want to make a differnt layout
Something like this plugin I have just found:
https://www.ads-software.com/extend/plugins/page-layout/
The problem with this one, is tha’t for some reason it ruins the site and just confusing everything in it, but this is the kind of plugin I need.

Also, how could I make pages that won’t appear on the menu?

did you look here: https://codex.www.ads-software.com/Pages#Creating_Your_Own_Page_Templates.
Just duplicate your page.php and call it myCustomPage.php. put this on top the new myCustomPage.php:

<?php
/*
Template Name: customPage
*/
?>

And change the myCustomPage.php to your liking
Now when you are making a a custom Page you can give it the customPage template

Awesome I found a solution. Thanks.
But about my other question: how could I open a page that won’t appear on the menu?

Use wp_list_pages() to make a menu and exclude pages like so:

<ul>
  <?php wp_list_pages('exclude=3,7,31'); ?>
</ul>

just link to the page that won’t appear on the menu with get_permalink()

Also, if your menu is created using the “Pages” Widget, there is an option to exclude pages by entering the ID # of the pages. If you’re using custom permalinks you won’t be able to see the ID’s and will need to use a plugin to display them, such as: https://www.ads-software.com/extend/plugins/simply-show-ids/

Oh, and I almost forgot about this plugin, which is probably perfect for what you want to do and much simpler:

https://www.ads-software.com/extend/plugins/exclude-pages/

When you create or edit a page, there is just a checkbox on the page for whether you want it to show up in menus or not. If you uncheck it, it’s not there. Very easy and doesn’t require messing with any code.

check out what this guy has to say about making a band site with wordpress..it’s simple and sweet so you might wanna skip ahead to part two. https://recordassault.com/?p=116

Actually, that page could be almost totally recreated easily, its just a bunch of sidebar widgets and a music player at the top.
MySpace has a pretty useful and good looking music player you could use, but there are several WP plugins that will do the task just fine.

Or just google search for a prebuilt theme that’s designed for bands, this one caught my eye: https://www.mybandtheme.com/, as well as a page that has several WP band & music themes listed: https://www.101bestwordpressthemes.com/blog/music-wordpress-themes.html.

One of the best things about wordpress is that you usually don’t have to reinvent the wheel, and don’t have to spend weeks coding something when chances are someone has already done it.