How to share contact of which information is changing

On an iPhone, sharing a contact’s phone number is a one-time action — you manually choose to share someone's number with another person, and once shared, it does not update automatically if the contact’s number changes later. This is a static, intentional act done by the user.

In contrast, sharing your contact photo and name on the Apple platform is an optional and ongoing feature. You can enable or disable it in Settings > Messages > Share Name and Photo. When enabled, your chosen photo and name can be automatically updated for people in your contacts list whenever you make changes — but only if they have the option to accept updates turned on. You remain in control, and this can be changed or turned off at any time.

So while both involve "sharing contact information," the phone number is a fixed one-off share, whereas the name and photo sharing is dynamic and customizable.