To be able to manage custom attributes in the user profile page in the account management console copy the template themes/base/account/account.ftl to the account type of your custom theme. Then open the copy in an editor.
As an example to add a mobile number to the account page add the following snippet to the form:
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Ensure the name of the input html element starts with user.attributes..
To see the changes make sure your realm is using your custom theme for the account theme and open the user profile page in the account management console.