Add the editor color palette to your site using wp_inline_style

functions.php

<?php

add_action( 'enqueue_block_assets', 'rgc_editor_color_palette', 15 );
/**
 * Add custom colors to the site using wp_inline_style, attached to the wp-block-library stylesheet.
 * Colors must be defined in your theme or functionality plugin.
 */
function rgc_editor_color_palette() {
	list( $colors, ) = (array) get_theme_support( 'editor-color-palette' );
	if ( ! $colors ) {
		return;
	}

	$css = '';
	foreach ( $colors as $color ) {
		$css .= sprintf(
			'.has-%1$s-color {color: %2$s;} .has-%1$s-background-color {background-color: %2$s;} ',
			$color['slug'],
			$color['color']
		);
	}

	wp_add_inline_style( 'wp-block-library', $css );
}