I think that the VarInt prefix is the number of bytes where:

• ASCII characters like A-Z are 1 byte
• Some characters like ẽ and ç are 2 bytes
• Emojis or non-Latin characters could be 3 or 4 bytes

Also, about line terminators, LF (\n) is usually used. CR (\r) is not commonly used.

I hope this helps! 😀