With just text-align:justify set, the browser will justify Tibetan text with embedded no-break spaces by stretching the spaces.

[r12a]

text-align:justify

Results:

• Gecko: ✅ Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:94.0) Gecko/20100101 Firefox/94.0
• Blink: ✅ _Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_157) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36
• Webkit: ✅ _Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_157) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.1 Safari/605.1.15

Related tests: Text alignment & justification