Add Custom Font Names to Elementor & GeneratePress Font Family drop-down

elementor-custom-fonts.php

/* ------------------------------------
/* CUSTOM FONTS
/* ------------------------------------ */

/* ELEMENTOR */
function modify_controls( $controls_registry ) {
    // First we get the fonts setting of the font control
    $fonts = $controls_registry->get_control( 'font' )->get_settings( 'options' );
    // Then we append the custom font family in the list of the fonts we retrieved in the previous step
    $new_fonts = array_merge( [ 'Biotif' => 'system' ], $fonts );
    // Then we set a new list of fonts as the fonts setting of the font control
    $controls_registry->get_control( 'font' )->set_settings( 'options', $new_fonts );
}
add_action( 'elementor/controls/controls_registered', 'modify_controls', 10, 1 );

/* GENERATEPRESS */
add_filter( 'generate_typography_default_fonts','jed_add_system_fonts' );
function jed_add_system_fonts( $fonts ) {
    $fonts[] = 'Biotif';
    return $fonts;
}