Download the Flash Player Projector.
Adobe Flash Player End of Life general information
www.adobe.com
You can also use the Newgrounds Flash Player
www.newgrounds.com
Ruffle exists as well
Ruffle is a Flash Player emulator written in Rust. Ruffle targets both desktop and the web using WebAssembly.
ruffle.rs
Just type "standalone flash player" in google if you're looking for anymore, there are so many