There is no switch so it is not available. If the asset is displayed in a template or list (image field) as an image then responsive generation would happen which means the browser will pick the appropriate image from the scrset array. The HIDPI checkbox is useful when you need to control assets used as interface elements and you don’t want them to scale down on HIDPI displays so you upload them @2x.
There is an old forum thread where this feature is explained by @bart and it is still relevant. → The HIDPI Feature - Publishing help / General - Forum | Webflow