Where should you begin when designing CX architecture?

Form follows function.  Before you worry about the architecture you need to define how best to serve/lead your various customer segments.  There are many ways to gather the 'voice of the customer' and that needs to happen first.  As the saying goes; "If you don't know where you're going any map will do."

We all know that CX is so much more than deploying a customer satisfaction survey. Just as if you were looking to design a new home for your family, we see the need for architects in CX. People who will take the time to understand your needs, preferences and intentions on how you plan to use the space – or, in the case of CX, use the insights. The architects help you allocate your budget to maximize the value.
some key elements to purposefully designing my approach to CX are
1) Listening to the Buyers
2) Understanding the Market 
3) Choosing the Best Materials
4) Having a Long-Term Plan

With customers.  It’s critical to get customer focus groups, digital surveys, and also behavioral tracking via APIs and clicks (eg. amplitude and Pendo) to get clarity both stated and unstated intent.  This will help prioritize key CX areas to improve or develop.