You can set privilege for the role “User” to control the user’s access to contacts. If this setting is enabled, then all the accounts with role “User” will only be able to view their own contacts instead of the default view of showing all contacts.

To enable access control, click on Settings from the top bar,

Click on User Management option from the left menu and then click on the "Show only contacts..." option to turn on this setting.

Now users will be able to view only their own contacts.