In Shopify, you can create customer segments based on the first purchase date, but if you record the first purchase date separately in the customer information, you can refer to it on your personal page, etc. This can be done by setting it in the customer tag and metafield separately.
Example of setting up to tag and metafield with customer's first purchase date
[How to set it up] Create a Flow that assigns a customer tag and sets metafields when an order is completed.
