How do we turn online off to fix inventory and redo some of the pages?
Turn on the storefront password page
https://help.shopify.com/en/manual/online-store/themes/password-page
To do this at a granular level per page you will need a theme customization or an app like locksmith.
The theme customization can either be based on customer tags if accounts are required to access your site , or using alternate templates with the add to cart button disabled.
For OS2.0 themes like Dawn this may be a setting you can turn off in an alternate template applied to those specific products you need to address.
If you need theme customization or consultation contact me.