How Do I set up an open or close button on my business or store
https://help.shopify.com/en/manual/online-store/shopify-vacation-setting
For daily closures with the online sales channel the basic way is to use storefront-password protection in tandem with a custom template design noting your hours.
https://help.shopify.com/en/manual/online-store/themes/password-page
Alternatively to automate close behavior use shopify-flow apps schedule trigger to setting a metafield that would in turn be used with advanced theme customizations for informing customers and disabling theme features like the buy-buttons(add to cart).
Example of scheduling https://shopify.com/admin/apps/flow/web/editor/templates/bdd77772-7f06-4bfc-b899-c4cecdd4626d
For a literally quick button you would need to use the api, with the simplest method being to publish a special barebones theme with basically no features in it.