- If you have a Daedalus for mainnet running on your machine, then that already contains a mainnet node. I see that there is a discussion of finding the location of its node socket here.
- Otherwise, you could install a mainnet node on your computer or on a cloud-based VM: How to run cardano-node | Cardano Developer Portal. There is a helpful Discord forum that discusses setting up a node where you can ask questions and hear advice.
- Another option is to use https://demeter.run/, which provides access to a mainnet node.
- Depending upon your use case, you might be able to use a service such as https://blockfrost.io/ to perform queries and submit transactions.