If you want to use two domain names for the same a website, there are a few ways to do it.
1. Set one domain as the primary domain
Build the website on example.com, then point the second domain to the same hosting account.
2. Redirect the second domain
Set a permanent 301 redirect from example.net to example.com. This is usually the simplest option if both domains represent the same business.
3. Use a domain alias
Some hosting panels, such as cPanel, allow you to add another domain as an alias so both domains can show the same website.
If the two domains are meant for completely different websites or sections, it's better to configure them separately rather than simply pointing both to the same site.
For SEO, I would normally choose one primary domain and redirect the other to it, rather than having two identical versions of the website.
Source: r/website_ideas · by /u/Rajjaque