Cathay Pacific allows you to change the flight and reschedule your journey to another date and time. You can change your travel online or through the customer service team. To reschedule Cathay pacific flight online, you can read further and enjoy your new travel with Cathay pacific:

To start, you need to open the Cathay pacific official website at your preferred browser on your device.
Then, you need to head towards the manage your trip option given at the top of the website.
With this, you need to add the passenger's first name, last name, and booking reference number.
Once you tap on the find booking option, you will get the details of your itinerary, and you need to search the flight you need to change.
After that, tap on the modify flight option and enter the new travel date with time.
With this, you will get the list of flights operated on your new date and choose the most suitable flight as per your needs.
Once you select the new flight, you will head towards the payment page and make the payment, if any.
Your existing flight will be canceled, and you will get the confirmation message of the new flight at your registered email id.

You can also hold on to someone at Cathay pacific and speak with the representative regarding the flight change. They will tell you the Cathay pacific flight change policy and help you change the flight with no extra fees or charges. You can find the different contact ways in their help section.

Get in detail at: https://www.faresjungle.com/blog/how-to-reschedule-cathay-pacific-flight