php - Guide me on How to enable Multiple domain Masking on a single page/file

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I am using CENTOS 7.8 (WHM/Cpanel)

Can anyone please guide me on how can anyone land their domain/subdomain after setting CNAME of my domain without changing their URL?

Example - my website is content.example.com

if someone points their subdomain mypics.mysite.in using cname then it should browse content.example.com without changing URL.