How to redirect from multiple domains to one?

Question

htaccess

There are 4 domains. One main and 3 additional. It is necessary to make a 301 redirect from them to the main one.
Note 1: all without www
Note 2: with https
Note 3: two of the three home domains are

Cyrillic

RewriteEngine on
RewriteCond %{HTTP_HOST} ^site.ru [OR]
RewriteCond %{HTTP_HOST} ^кириллический1.XN--P1AI [OR]
RewriteCond %{HTTP_HOST} ^кириллический2.XN--P1AI
RewriteRule ^(.*)$ https://mainsite.ru/$1 [R=permanent,L]

Relay works only from site.ru to https://mainsite.ru/

Answer 1

RewriteCond %{HTTP_HOST} ^(www\.|)9918474\.ru$     [NC,OR]
RewriteCond %{HTTP_HOST} ^(www\.|)site4top\.ru$    [NC,OR]
RewriteCond %{HTTP_HOST} ^(www\.|)sunnyfruits\.ru$ [NC,OR]
RewriteCond %{HTTP_HOST} ^(www\.|)u-kit\.ru$       [NC,OR]
RewriteCond %{HTTP_HOST} ^(www\.|)mediagrup\.ru$   [NC,OR]
RewriteCond %{HTTP_HOST} ^(www\.|)vmast\.ru$       [NC,OR]
RewriteCond %{HTTP_HOST} ^(www\.|)desid\.ru$       [NC]
RewriteRule ^(.*)$ https://klondike-studio.ru/  [R=301,L]

Don't forget to escape the dot.
in order to make these redirects, you do not need to create sites, just add aliases to the main site

and enter all the rules in its htaccess.
This will allow you not to create a bunch of sites with different htaccess, and yes, then this syntax will be enough for you.
If you already have sites, then all the rules should be in each site in its .htacess