How to refresh the Access token from using refresh token when expired

I am moving the Dropbox app authentication flow to use short lived tokens with refresh tokens. I need the app to work just like it worked with a long lived tokens before.

I learned that I can get a refresh token and use that in subsequent calls to SDK methods without reauthorizing the access.

1. I understand that once the initial Access token is expired, it is no longer usable. But we continue to use the refresh token without updating the access token. Is there a way that I can get a new Access Token using the refresh without going through the authorization process again? (I want this to be happened without end user action)

2. Although we dont update the Access token, I believe the SDK is retrieving a new access token in the background, every time we call a method using the refresh token. But I dont find a method that returns this new Access token. If I get this Access token, I can store it and use it again within the allowed period. This will reduce some calls done in the SDK to get a new Access token.

Can you please answer the above and verify if my understanding is correct?

**Versions**
* What version of the SDK are you using? 5.5
* What version of the language are you using? .net 4.8
* What platform are you using? Web based