Are there options without buying a certificate for the site.ru domain to redirect from https://site.ru to https://site.com?

Question

Web development

there are 2 domains site.ru and site.com an
SSL certificate was purchased for site.com
redirects are configured correctly in .htaccess, BUT
when you go to https://site.ru (they didn’t buy or install a certificate on it), a message is displayed in the browser about insecure connection.

Are there options without buying a certificate for the site.ru domain to redirect from https://site.ru to https://site.com

If not, then give a link to the mat. the part where you can read - why this can not be done)

In the console, you can use other software
wget https://site.ru --no-check-certificate

But you need to redirect ordinary users in the browser.