It is really not a sophisticated difficulty. Some hosts like FlyWheel (https://getflywheel.com) will allow you to launch a brand new occasion of WordPress utilizing a brief area, like https://chosungmin.flywheelsites.com
and you’ll then construct your new WordPress web site there and when you’re completed you simply swap over your DNS settings to level to their new IP.
That is the best approach to do it – simply construct some other place with a unique, non permanent area after which while you’re prepared, swap it throughout.
You may additionally simply add a sub-directory to your present web site… …so in case your website is https://chosungmin.com, you’ll construct your new website in https://chosungmin.com/new-site/
After which while you’re carried out, you may simply make a redirect or you may transfer the entire thing to the basis listing.
There are many methods to do that.