This might be what I need

I am starting to build websites for local businesses & to be honest all my own sites i have built I just build as they are live.

I wanted to be able to, for clients, build, show them, then have it go live. So I figured I needed like a demo or staging site. With this plug in can you continue to build your site as normal (to clarify I dont build then upload via FTP – WP is already built in within my hosting company control panel)
& then if you untick this plug in it shows your finished site ? Or does it not work like that ?

https://www.ads-software.com/plugins/yith-pre-launch/