Microsoft Graph API support for on premise Exchange

In specific, check out the following statement in the subsequent link of the shared link:
"But we have no plans currently to change the way EWS works on-premises, so using Graph for Exchange Online and EWS for Exchange Server on-premises is the current recommendation."

(this comes with the hint that you can also https://learn.microsoft.com/en-us/exchange/client-developer/exchange-web-services/how-to-authenticate-an-ews-application-by-using-oauth for accessing Exchange Online only, if the Graph API switch does not work for you)