Title of the question is self-explanatory, almost.
When user creates a new contact via new button on contact page, there are certain field required for this user. However, when the same user created a contact via global action called "New Contact". this field is not appears to be as not required.
I know that I can make this field required. But then it'll be required for every user.
How can I make this field required in global action only for one specific user?
I don't think Salesforce provides an out-of-the-box way to directly make fields required for certain users in a Global Action Layout.
To achieve this functionality, you can consider using a combination of custom components and custom validation. Below is a high-level outline of how you can approach this:
Create a Custom Lightning Component: Build a custom Lightning component that represents your Global Action Layout. This component will include the field and any other necessary fields.
Implement Validation Logic: Within the Lightning component's controller or helper, implement the validation logic that checks whether the field should be required for the current user.
