Custom page created by a wordpress plugin - wordpress

Question

I am trying to figure out how to create a Wordpress plugin that adds a page to the Wordpress website on which it is installed.
I came up with the following which works and adds the page.
However, it's far from what I am trying to achieve:
How to change the entire page? Not just the content? Right now, it has all the header and footer and navbar.
How to have PHP code in the page, not just static content?
Is it possible to have everything under a url (https://some-url.com/my-plugin/) routed to this same page?
For example:
https://some-url.com/my-plugin/ -> run my page
https://some-url.com/my-plugin/foo/ -> run my page
https://some-url.com/my-plugin/foo2/abc/ -> run my page
etc.
<?php
/**
* Plugin Name: MyPlugin
* Plugin URI: myplugin.com
* Description: MyPlugin
* Version: 1.0
* Author: Mike
* Author URI: myplugin.com
*/
define( 'MYPLUGIN__PLUGIN_DIR', plugin_dir_path( __FILE__ ) );
function create_page() {
$post_data = array(
'post_title' => 'Test of my plugin',
# How to change the entire page? Not just the content?
# Also, how to have PHP code in the page, not just static content?
'post_content' => 'Place all your body content for the post in this line.',
'post_status' => 'publish', // Automatically publish the post.
'post_type' => 'page', // defaults to "post".
'post_name' => 'my-plugin', // url slug (will 'slugify' post_title if empty) https://some-url.com/my-plugin-page?/
);
// Lets insert the page now.
wp_insert_post( $post_data );
}
function plugin_activation() {
create__page();
}
function plugin_deactivation() {
}
register_activation_hook( __FILE__, 'plugin_activation' );
register_deactivation_hook( __FILE__, 'plugin_deactivation' );

Answer 1

You want wp_insert_post()
Usage:
$postarr = [
'post_title' => 'My Page Title', // <title> tag
'post_content' => '<p>page content</p>', // html for page content
'post_type' => 'page', // blog post is default
'post_name' => 'my-plugion-page', // url slug (will 'slugify' post_title if empty) https://some-url.com/my-plugion-page?/
];
$post_id = wp_insert_post($postarr);
For example, in your $postarr if you want it to be a page (not a blog post), use 'post_type' => 'page'. For the page title 'post_title' => 'My New Page' and so on.
See: https://developer.wordpress.org/reference/functions/wp_insert_post/
Updated for additions to user question
If you don't want it to follow the theme templates, then you'll need to hook into the 'page_template' filter and use a template file you create in your plugin. See: https://wordpress.stackexchange.com/questions/3396/create-custom-page-templates-with-plugins
Depends on the situation, you can add code in your custom template, use shortcodes or custom Gutenberg blocks. You can use Advanced Custom Fields on in the Admin UI and use get_field() in your code, etc. You have lots of options in WordPress. Once you have a custom template you can just add regular PHP in there.
Yes, but you'll need to use regex and create rewrite rules using add_rewrite_rule(). Here are links that help with creating rewrite rules in WordPress
add_rewrite_rule
add_rewrite_tag
flush_rewrite_rules
WP_Rewrite API