How to adjust Apache webserver (through .htaccess files) to run Magento in a subdirectory?

If you have installed Magento 2 into a subdirectory (/store, for example) then you should adjust your webserver.
If you webserver is Apache then you can do the adjustment through the 4 Magento 2 .htaccess files:

  1. .htaccess

Find the RewriteEngine on line:

Place the following code right after the line above:

RewriteCond %{REQUEST_URI} !^/store/
RewriteRule ^(.*)$ /store/$1

Replace store with your subdirectory path.

How settings should be for subdomain?

Can you give an example?

You should navigate the standard Magento 2 .htaccess files and just do that I described above.

But how?
address domains (shop subdomain)

Can you share accordingly.

I’m a rookie.

You should not specify a domain in the .htaccess files. You should specify the subfolder only. See the top post: the subfolder is /store/ in my case.

What is your full path/directory ? where is /store/ located ?

The /store/ is not a folder: it is a path in the store’s URLs.
Please see the RewriteCond and RewriteRule documentation.