Is this a proper way to load CSS files into my WordPress child theme?

add_action( 'wp_enqueue_scripts', 'my_theme_enqueue_styles' );
add_action( 'wp_enqueue_scripts', 'case_studies_styles' );
add_action( 'wp_enqueue_scripts', 'about_styles' );

function my_theme_enqueue_styles() {
    wp_enqueue_style( 'child-style', get_stylesheet_uri(),
        array( 'parenthandle' ), 
        wp_get_theme()->get('Version') // this only works if you have Version in the style header
    );
}

function case_studies_styles() {
    wp_enqueue_style( 'child-casestudies', get_stylesheet_directory_uri() . '/casestudies.css', array(), rand());
}

function about_styles() {
    wp_enqueue_style( 'child-about', get_stylesheet_directory_uri() . '/about.css', array(), rand());
}

I'm asking because I've asked some people to try to load my site, and some of them don't get the stylesheets at all and just get the blank HTML code.

Also, in the beginning of all CSS files, I have this beginning. Every CSS file has a different version (1.2,1.1,1.0)

/*
 Theme Name:   GeneratePress Child
 Theme URI:    
 Description:  Default GeneratePress child theme
 Template:     generatepress
 Version:      1.2
*/

EDIT: I've tried this too, but still no effect.

function my_theme_enqueue_styles() {
    wp_enqueue_style( 'child-style', get_stylesheet_directory_uri() . '/style.css', wp_get_theme()->get('Version'));
}

function case_studies_styles() {
    wp_enqueue_style( 'child-casestudies', get_stylesheet_directory_uri() . '/casestudies.css', wp_get_theme()->get('Version'));
}

function about_styles() {
    wp_enqueue_style( 'child-about', get_stylesheet_directory_uri() . '/about.css', wp_get_theme()->get('Version'));
}