Apache Redirect

https://serverfault.com/questions/344614/simple-apache2-redirect-from-one-domain-to-another

https://www.digitalocean.com/community/questions/how-to-redirect-https-ip-to-https-domain

https://stackoverflow.com/questions/33874212/htaccess-redirect-https-to-another-https

You cannot match scheme http:// in RewriteCond %{HTTP_HOST}.

You can use this rule:

RewriteEngine On

RewriteCond %{HTTP_HOST} !^www\.domain\.com$ [NC]
RewriteRule ^ https://www.domain.com%{REQUEST_URI} [R=302,L]

You can use the RedirectPermanent directive to redirect the client to your new URL.

Just create a very simple VirtualHost for the old domain in which you redirect it to the new domain:
<VirtualHost *:80>
    ServerName xy.example.com
    RedirectPermanent / http://abc.example.com/
    # optionally add an AccessLog directive for
    # logging the requests and do some statistics
</VirtualHost>