Scatter has a testnet which enables you to experiment with deploying and modifying collections for free.
The Scatter testnet is available for Sepolia here: https://sepolia.scatter.art/
The testnet is still a public blockchain so anything you publish there will still be visible to others. With that in mind, we recommend you use dummy data, text, and images when deploying your testnet collection. Eventually every testnet is retired but this can take years to happen and it's likely someone somewhere will still archive it.