Is this how you change domain name on the same host?

I was dumb enough to get a misspelled domain and lazy enough to change it on time and now I have a well-established site with plenty of ranking keywords that I need to update the domain name and I’m scared that I will lose the rankings.

I read the internet a lot about how to change a domain name but before I start I want to make sure I got everything right.

1. So I have the OldDomain live on my OriginalHost.
2. I create a new account in cPanel for the NewDomain to create a new separate directory for the NewDomain on the same host.
3. I enter the directory folder for the NewDomain and copy all the WordPress files from the OldDomain.
4. Copy the database from the OldDomain to NewDomain too.
5. Now I’m updating the URL in wp-config to reflect the URL of the NewDomain.
6. Change the nameservers of NewDomain to point to OriginalHost.
7. Now both NewDomain and OldDomain should be live on the same host, with the exact same content, but no redirects, right?
8. The only thing now is to build a 301-header for the OldDomain (via cPanel or .htaccess) to redirect 1:1 to NewDomain.

Please correct me if I’m missing a step.

I also have a question:

Once I have done all the above steps and the NewDomain is live, can I delete all the files from the server directory of OldDomain and only keep the .htaccess for the redirects?

And what’s the best way to do a 1:1 301 redirect for all the existing URLs, like I want OldDomain.Com/random-page-123 to redirect to NewDomain.Com/random-page-123