How to change the locale in chrome browser

Based from this thread, you need to bookmark chrome://settings/languages and then Drag and Drop the language to make it default. You have to click on the Display Google Chrome in this Language button and completely restart Chrome.

[on hold: broken in Chrome 72; reported to work in Chrome 71]

The "Quick Language Switcher" extension may help too: https://chrome.google.com/webstore/detail/quick-language-switcher/pmjbhfmaphnpbehdanbjphdcniaelfie

The Quick Language Switcher extension allows the user to supersede the locale the browser is currently using in favor of the value chosen through the extension.

Open chrome, go to chrome://settings/languages

On the left, you should see a list of languages. Use mouse to drag the language you want to the top, that will change the order for the values in Accept-language of requests.

If you still don't see the language you prefer, it may be cookies. Go to cookies and clean it up you should be good.

Feb, 2022 Update:

On Chrome, press F12 to open Developer Tools:

Then, press Esc to open another panel which has Sensors tab:

Finally, you can set the Locale like "ja-JP" by choosing the Location, "Tokyo" as shown below:

If there isn't Sensors tab, you can open it from the 3 dots as shown below:

I use this function for testing internationally launched website.