Testing multilingual sites without changing OS settings is possible by emulating language and writing mode attributes directly. Key areas to check include the `lang` and `dir` HTML attributes, browser locale for I18n API formatting, and layout behavior under different text lengths. Using logical CSS properties (like `margin-inline-end` and `text-align: end`) instead of physical ones ensures layouts adapt correctly to RTL languages. Tools like Polypane's emulation panel and Content Chaos feature let developers simulate RTL direction, locale-specific date/number formatting, and longer or shorter text without full translations.
