Firefox
The steps below apply to Firefox desktop. HTTPS-only for mobile is currently only available in Firefox Developer mode, which advanced users can enable in about:config.
Settings > Privacy & Security > Scroll to Bottom > Enable HTTPS-Only Mode
Chrome
HTTPS-only in Chrome is available for both desktop and mobile in Chrome 94 (released today!).
Settings > Privacy and security > Security > Scroll to bottom > Toggle “Always use secure connections”
This feature is also under the flag chrome://flags/#https-only-mode-setting.
Edge
This is still considered an “experimental feature” in Edge, but is available in Edge 92.
- Visit
edge://flags/#edge-automatic-httpsand enable Automatic HTTPS - Hit the “Restart” button that appears to restart Microsoft Edge.
Visit edge://settings/privacy, scroll down, and turn on “Automatically switch to more secure connections with Automatic HTTPS”.
Safari
HTTPS is upgraded by default when possible in Safari 15, recently released September 20th, for macOS Big Sur and macOS Catalina devices. No setting changes are needed from the user.
Updates for Safari 15
Source: https://www.eff.org/https-everywhere/set-https-default-your-browser