For enabling Attributes, we have to disable the “Customize Login Page” under Branding → Universal Login.
Even after enabling Attributes, while trying to change the Verification Method from Email Verification Link to OTP, its throwing a error “Error!Email verification using otp is only compatible with Identifier First.”
Identifier First option under Authentication → Authentication Profile means no Custom Login Page.
Is there a way to achieve Email Verification with OTP for applications that have custom login page.
You are correct, it appears to be by design that Email OTP verification requires the use of Identifier First Authentication profile of the Universal Login, in order to enhance the security and streamline user experience.
While Custom Login Pages get disabled in this flow, the recommendation is to migrate to the Universal Login if possible, as it offers high customizability to match your branding and theme for your users. Using Liquid template language you retain control over the HTML and CSS of the login page templates and are able to adjust the prompts as required.