Automatically submitting records for approval
Key Takeaway
For a Classic Approval Process, submit records automatically with a record-triggered flow that runs the Submit for Approval flow action. For a Flow Approval Process, use the Record-Triggered Flow Approval Process type, because the Submit for Approval flow action doesn't submit records to Flow Approval Processes.
Users usually start an approval by clicking a button to submit a record, but they can forget to. Salesforce can submit records automatically when they're created or edited, so approval doesn't depend on someone remembering. How you set this up depends on whether the record goes to a Classic Approval Process or a Flow Approval Process.
Submitting a record by hand
With a Classic Approval Process, users submit a record by hand by clicking the "Submit for Approval" button on the page layout. If the org's Lightning record pages use Dynamic Actions, add the Submit for Approval action to the record page's highlights panel instead.