How To Redirect Whole site to another site except the Root Page

I want to redirect every url of my site except the root i.e., the home index.html

Basically I want everything after the / to redirect.

For example: If I visit website.com it should normally show the index.html page placed in the root. But if I goto website.com/someurl then it should redirect to website2.com/someurl

The site shouldn't redirect only for the root (home) page, and Should redirect for all other links.

Please help me with the relevant .htaccess code.

Thank You