I am trying to audit what work a user has done in Netsuite. I know that the transaction line history shows when a user has made a change to a transaction line. Is there any way to get a full list of changes to any transaction that a single user has made? Any way to access that line level history?

Apart from the individual transaction line level history, there is an audit trail tab on transactions called "System Information" which shows edit/change history for the transaction itself including workflows. If you need to audit activity/change history by user or by transaction type etc then you're looking for Administration & Controls>Audit.

Transactions --> Management --> View Audit Trail. You can view all the changes done by a user. Have to validate it for line level changes