Is it possible to edit Bitcoin Core to remove the
IsStandard function and broadcast non-standard transactions?
Also is there a version like this available already?
You can change your node to broadcast a non-standard transaction, but other nodes following consensus rules will not pass your transaction along. The only way to include a non-standard transaction in the blockchain is to contact a miner and ask them to include it in a block.
Bitcoin's testnet has IsStandard disabled. If you are trying to test scripts, it is strongly recommended to do it on testnet or regtest.