weekly-booking.php

<?php
add_action( 'wp_footer', function() {
	echo '<script>
		jQuery( document ).on( "jet-booking/init-field", ( $event, $field ) => {
			var silent = false;
			var format = $field.data( "format" ) || "YYYY-MM-DD";
			$field.bind( "datepicker-change", ( event, obj ) => {
				silent = ! silent;
				if ( silent ) {
					$field.data( "dateRangePicker" ).setEnd( moment( obj.date1 ).add( 7, "d" ).format( "YYYY-MM-DD" ) );
				}
			} );
		} );
	</script>';
}, 99 );