Load Extra font variants in Astra Google Fonts.

astra-extra-google-font-variants.php

<?php // don't copy this line in your code

/**
 * Load extra font weights in Astra Google fonts.
 * This example loads extra variannts for the Open Sans font.
 *
 * @param Array $fonts Fonts selected in customizer.
 * @return Array Fonts array updated with more font variants to be loaded.
 */
function your_prefix_astra_more_font_weights( $fonts ) {
    if ( isset( $fonts["'Open Sans', sans-serif"] ) ) {
        $fonts["'Open Sans', sans-serif"] = array( '400', '400i', '700', '700i'  );
    }

    return $fonts;
}

add_filter( 'astra_google_fonts', 'your_prefix_astra_more_font_weights' );