site title link different page than main page

The site title is by default always linked to the homepage. To change that functionality for one specific page would require first creating a child theme, and then adding a PHP condition to check and modify the site title link for just that specific page.

Making a child theme means your changes won’t be overwritten when you update the theme. If you’re new to child themes, you can explore these guides:

https://codex.www.ads-software.com/Child_Themes
https://www.smashingmagazine.com/2016/01/create-customize-wordpress-child-theme/