.htasses redirect question?

Question

htaccess

You need to install the second site in a separate folder, but for it to be available at a different address.
For example, the second site is located here "site/folder-1/folder-2"
And for the second site to open and work at the address site/folder-3 The main thing is that the subfolder also opens at the address site/folder-3 /
....
to tell not readdressing, and substitution of the address. I don't know exactly how to call it.
RewriteEngine
On
RewriteCond %{REQUEST_URI} ^/folder-3 [NC]
RewriteRule folder-3(.*) /folder-1/folder-2/$1 [L]