<?php


function my_namespace_register_theme_support(){

    add_theme_support( 'slug-of-feature' );

    add_theme_support( 'slug-of-feature', $args );


}

add_action( 'after_theme_setup', 'my_namespace_register_theme_support' );

<?php


function my_namespace_register_theme_support(){

    add_theme_support( 'align-wide' );

    add_theme_support( 'align-full' );


}

<?php


function my_namespace_register_theme_support(){

add_theme_support( 'editor-color-palette', array(
    array(
        'name' => __( 'strong magenta', 'themeLangDomain' ),
        'slug' => 'strong-magenta',
        'color' => '#a156b4',
    ),
    array(
        'name' => __( 'light grayish magenta', 'themeLangDomain' ),
        'slug' => 'light-grayish-magenta',
        'color' => '#d0a5db',
    ),
    array(
        'name' => __( 'very light gray', 'themeLangDomain' ),
        'slug' => 'very-light-gray',
        'color' => '#eee',
    ),
    array(
        'name' => __( 'very dark gray', 'themeLangDomain' ),
        'slug' => 'very-dark-gray',
        'color' => '#444',
    ),
) );

}

<?php


function my_namespace_register_theme_support(){

add_theme_support( 'editor-font-sizes', array(
    array(
        'name' => __( 'Small', 'themeLangDomain' ),
        'size' => 12,
        'slug' => 'small'
    ),
    array(
        'name' => __( 'Normal', 'themeLangDomain' ),
        'size' => 16,
        'slug' => 'normal'
    )
  ) );

}

/* Main column width */
.wp-block {
    max-width: 720px;
}

/* Width of "wide" blocks */
.wp-block[data-align="wide"] {
    max-width: 1080px;
}

/* Width of "full-wide" blocks */
.wp-block[data-align="full"] {
    max-width: none;
}

/* Custom Colour classes */

.has-strong-magenta-background-color {
    background-color: #313131;
}

.has-strong-magenta-color {
    color: #f78da7;
}
}

/* Custom Font Size classes */

.has-regular-font-size {
    font-size: 16px;
}

.has-huge-font-size {
    font-size: 48px;
}

<?php 


function my_namespace_declare_theme_support(){

    add_theme_support('disable-custom-font-sizes');


    add_theme_support( 'disable-custom-colors' );


}



add_action( 'after_theme_setup', 'my_namesapce_declare_theme_support' );