Hi Rafael,
Thank you for contacting WP Travel team.
Actually, if you are willing to show the partial payment option only in the payment mode, please add the following given filter code in the functions.php file of your child theme.
function wptravel_customize_booking_option( $fields ) {?
$fields['payment_fields']['payment_mode']['default'] = 'partial';?
$fields['payment_fields']['payment_mode']['options'] = array( 'partial' => 'Partial Payment' );??
return $fields;?
}?
add_filter( 'wp_travel_checkout_fields', 'wptravel_customize_booking_option' );
For detail regarding creating a child theme, please once refer below-given link:
https://wptravel.io/how-to-create-a-child-theme/
Also, If you are willing to show the Booking with payment option then you can select the option by going to Admin Panel > WP Travel > Settings > Checkout.
For detail regarding how to add the option under the booking option then please once refer below-given link:
https://wptravel.io/setting-of-booking-option-in-the-checkout-page/
Hope this helps.
If you have any queries further, please let us know.