Multiple array for post_content on plugin activation

You just add the content to your initial array. The most simple way is using the titles as array indices like this:

$pages = [
    'Login'     => 'Some content',
    'Dashboard' => 'Some other content'
];

foreach ( $pages as $title => $content ) 
{       
    if ( get_page_by_title( $title ) ) {
        continue; // skip this page
    }
    
    wp_insert_post([
        'post_title'    =>  $title,
        'post_content'  =>  $content,
        'post_status'   =>  'publish',
        'post_author'   =>  get_current_user_id(),
        'post_type'     =>  'page',
   ]);
}