When you order a domain name, it will no longer be possible to change it.
It will be necessary to order the new domain name and let the first one expire and fall back into the public domain.
Example 1:
I ordered the domain MONDOMAINE.FR
I can't rename it to MONDOMAINE.COM
Example 2:
I ordered the domain MONDOMAINE.FR
I can't rename it to MY DOMAIN.FR
Example 3:
I ordered the domain MONDOMAINE.FR
I can't rename it to MYAUTREDOMAINE.FR