If you have a approval flow for each and every records and you want to trigger mail to inform approver that this specific record is waiting for your approval then we can create a logic that approver can directly approve or reject that record from mail template.

Let's consider if you trigger one mail to inform the user for any specific task and he needs to take action from that mail itself, So in that case we can create one API with whatever action end user needs to inform on that mail and we will pass that API link on that mail template so whenever user will click on that link API will be triggered and that action will run.