Is this possible to redirect a free running shoes Wix blog on a new custom domain or an already exisiting domain of my website?
Wix Blog is a Wix app and therefore you are better going through Wix Support for more help with your issue and reading the Wix Support pages for the Wix Blog.
https://support.wix.com/en/article/contacting-wix-support
https://support.wix.com/en/new-wix-blog/setting-up-the-new-wix-blog
https://support.wix.com/en/article/setting-up-a-301-redirect-to-a-specific-blog-post