Redirect Domain Using DNS Settings

[tgecks]

Hello,

I have purchased two domains through Shopify, and I want people entering that second domain to be redirected to a specific page, not the primary domain.

E.g., I have the domains  "https://mydomain.com" and "https://my2nddomain.com". When people enter "my2nddomain.com" in their browser, I want them to get directly to "https://mydomain.com/pages/thatpage".

As I understand, this needs to be done in the DNS settings. How can I do it?

Thanks in advance!