Hi Karthikeya,
You can create two deeplink microflows ( one for approve and one for reject), and give their URL in the email buttons as href, Now in the deeplink URL you can expect a GUID of the Request object itself and then perform the logic of approving or rejecting the request.
Now, once the user clicks on the button, the respective microflow will get triggered, and your logic would be Performed.
Hope it helps!