Add CSS classes and inline styles for colors to the incoming attributes array.

This will be applied to the block markup in the front-end.

function wp_apply_colors_support( $block_type, $block_attributes ) {
	$color_support = _wp_array_get( $block_type->supports, array( 'color' ), false );

	if (
		is_array( $color_support ) &&
		wp_should_skip_block_supports_serialization( $block_type, 'color' )
	) {
		return array();
	}

	$has_text_colors_support       = true === $color_support || ( is_array( $color_support ) && _wp_array_get( $color_support, array( 'text' ), true ) );
	$has_background_colors_support = true === $color_support || ( is_array( $color_support ) && _wp_array_get( $color_support, array( 'background' ), true ) );
	$has_gradients_support         = _wp_array_get( $color_support, array( 'gradients' ), false );
	$color_block_styles            = array();

	// Text colors.
	if ( $has_text_colors_support && ! wp_should_skip_block_supports_serialization( $block_type, 'color', 'text' ) ) {
		$preset_text_color          = array_key_exists( 'textColor', $block_attributes ) ? "var:preset|color|{$block_attributes['textColor']}" : null;
		$custom_text_color          = _wp_array_get( $block_attributes, array( 'style', 'color', 'text' ), null );
		$color_block_styles['text'] = $preset_text_color ? $preset_text_color : $custom_text_color;
	}

	// Background colors.
	if ( $has_background_colors_support && ! wp_should_skip_block_supports_serialization( $block_type, 'color', 'background' ) ) {
		$preset_background_color          = array_key_exists( 'backgroundColor', $block_attributes ) ? "var:preset|color|{$block_attributes['backgroundColor']}" : null;
		$custom_background_color          = _wp_array_get( $block_attributes, array( 'style', 'color', 'background' ), null );
		$color_block_styles['background'] = $preset_background_color ? $preset_background_color : $custom_background_color;
	}

	// Gradients.
	if ( $has_gradients_support && ! wp_should_skip_block_supports_serialization( $block_type, 'color', 'gradients' ) ) {
		$preset_gradient_color          = array_key_exists( 'gradient', $block_attributes ) ? "var:preset|gradient|{$block_attributes['gradient']}" : null;
		$custom_gradient_color          = _wp_array_get( $block_attributes, array( 'style', 'color', 'gradient' ), null );
		$color_block_styles['gradient'] = $preset_gradient_color ? $preset_gradient_color : $custom_gradient_color;
	}

	$attributes = array();
	$styles     = wp_style_engine_get_styles( array( 'color' => $color_block_styles ), array( 'convert_vars_to_classnames' => true ) );

	if ( ! empty( $styles['classnames'] ) ) {
		$attributes['class'] = $styles['classnames'];
	}

	if ( ! empty( $styles['css'] ) ) {
		$attributes['style'] = $styles['css'];
	}

	return $attributes;
}