Xero knows when an invoice is due. It does not know what the contract said about when to raise it, and it does not know that this particular client always pays on the 45th day whatever you send them.
The automated version reads the contract terms once. Monthly on the 1st, or on delivery of each milestone, or 50 percent up front. It raises each invoice in Xero on that date, with the line items from the agreed scope, and sends it from your email with your usual two lines. Seven days before due, a polite note. On the due date, a shorter one. Seven days after, a plainer one, and you get a message on Slack with the client name and the amount, which is the first time you hear about it.
If the client pays, the chasing stops the same hour, because the system watches the bank feed. If they pay the wrong amount, it tells you that too.
The raising matters more than the chasing. Invoices that go out on the day the contract says, every time, get paid faster than invoices that go out when someone remembers.
This is the kind of thing we build. It runs in your own accounts.