Can I interact with tesnet without running a testnet node?

I am trying to make RPC calls and send raw transactions on the testnet, but can't figure out how to do this without running a full node.

I have installed bitcoin core, and put chain=test in the config, but don't know what to do next. Are there full testnet nodes that accept public RPC calls?

I would also like to do this on the mainnet if possible (make RPC calls and send raw transactions).

I am new to this and the bitcoin software confuses me to no end, any help would be appreciated, thanks! :)