It's 2025, and there's a lot of outdated docs on programming ATtiny microcontrollers (ATtiny85, ATtiny84, etc.) on Arduino. You CAN do this on Arduino IDE 2.x on Windows 11.

The core you want is ATTinyCore. To install it:

• This core can be installed using the boards manager. The boards manager URL is:
  http://drazzy.com/package_drazzy.com_index.json
• File→Preferences on a PC, or Arduino→Preferences on a Mac, enter the above URL in "Additional Boards Manager URLs"
• Tools → Boards → Boards Manager…, Select "ATTinyCore by Spence Konde" and click "Install".

You can program it several ways. Here's two:

• USBasp: A dirt cheap dedicated USB programmer. USBtinyISP wasn't tested, but likely works similarly.
• Arduino as ISP: Use an existing Arduino Uno, Nano, or similar as a programmer. I'm not gonna document this approach, but it googles easily.