How do I (automatically) earn interest after depositing assets?

Vertex is built with an integrated money market at it’s core.
When you deposit assets into the protocol, other traders can borrow those assets to take leverage. Think of it like any other money market dApp; if a borrower’s loan-to-value, or in this case margin ratio, gets too low they will risk liquidation. Lenders are secured through smart-contracts and don’t need to rely on human trust.
So, TLDR; by default whenever you deposit assets to trade on Vertex those assets start earning interest.