If you don't want to download third-party software, you can use the native Windows Character Map to find Sinhala glyphs: Press Win + R , type , and hit Enter.
You can copy individual characters or a group of characters to the clipboard, and then paste them into any compatible program. Or, Microsoft Support Abhaya Libre - Google Fonts sinhala character map download free
A portable, phonetic Unicode character converter. It doesn’t require installation and allows you to type "Singlish" (phonetic English) to generate Sinhala characters instantly. If you don't want to download third-party software,
A popular choice for mobile and desktop users that simplifies Sinhala Unicode typing. How to Use the Built-in Windows Character Map for Sinhala sinhala character map download free