Forgot security question

I'm writing to tell you about my problem with ICloud ,

I recently have bought Iphone 11 (128G)

Although, I could sign in to my ICloud with web browser, I couldn't set up my ICloud as my apple Id (****@ gmail.com) on my iphone.

beside , unfortunately I forgot the answer of my security question.

I appreciate a reply at your earliest convenience

Thanks for your support

[Edited by Moderator]