to add a button inside payment settings?

add-gateway-settings.php

<?php

/**
 * Register the new field in the array of settings fields for the gateway 
 * 
 * @hooked woocommerce_settings_api_form_fields_{$gateway_id}
 * 
 * @param array $settings The gateway's existing settings.
 *
 * @return array
 */
function add_my_field_to_settings( array $settings ): array {
	$settings[] = array(
		'id'   => 'my_new_field_config',
		'type' => 'my_new_field',
	);
	return $settings;
}
add_filter( "woocommerce_settings_api_form_fields_{$gateway_id}", 'add_my_field_to_settings' );

/**
 * Output the settings field.
 *
 * @hooked woocommerce_admin_field_my_new_field
 * @see \WC_Admin_Settings::output_fields()
 *
 * @param array<string, mixed> $value The get_settings() configuration with the saved $value in its `value` key.
 */
public function print_my_new_field( array $value ): void {
	echo "<button>HERE</button>";
}
add_action('woocommerce_admin_field_my_new_field', 'print_my_new_field');