301 code for changing the domain name of the website without losing traffic

Generally speaking, it is not recommended to change the domain name unless there is no other way. For example, for well-known reasons, I have to change my .cn domain name to a .com domain name, and I can only do a 301 redirect.
Either the domain name is blocked, such as free8.com is blocked and needs to be changed.
Here is the jump code:

# BEGIN WordPress
Options +FollowSymLinks
RewriteEngine on
rewritecond %{http_host} ^www.old.com [nc]
rewriterule ^(.*)$ http://www.new.com/$1 [L,R=301]
# END WordPress

Among them, www.old.com is replaced with your old domain name, and www.new.com is replaced with your new domain name. This is suitable for linux PHP code, used in .htaccess file.