Simplicity is still just a concept and as far as I know not even yet being implemented in earnest. I think you'll still have to wait a couple of years until Simplicity as a platform will become available for developers to play around with.
Meanwhile just keep an eye on the Bitcointalk forums and r/bitcoin, some news will surely emerge once Simplicity reaches a state were it gets interesting. If you want to keep a really close eye on things, or maybe even contribute to Simplicity itself, subscribe to the Bitcoin dev mailing list and follow the discussion:
https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev