Refresh Token POST Request to the Token Endpoint
When the access token expires, the application can send the refresh token POST request to the token endpoint to get a new access token.
The format of the URL is:
‘https://<accountID>.suitetalk.api.netsuite.com/services/rest/auth/oauth2/v1/token’
where <accountID> represents your NetSuite account ID.

Request Parameters for the Refresh Token Request
- grant_type: The value of the grant_type parameter is
refresh_token - refresh_token : The value of the refresh_token parameter is in JSON Web Token (JWT) format.

in Authorization gave Type as basic Auth and Client ID & Secret as Username and Password.

Send Request
Will get new access token after expiration

Request to the Logout Endpoint
The application sends a GET or POST request to the logout endpoint to revoke the valid id token and its associated access and refresh tokens. This endpoint has the following format:
‘https://<accountID>.suitetalk.api.netsuite.com/services/rest/auth/oauth2/v1/logout’
where <accountID> represents your NetSuite account ID.

Request Parameters for the Logout Token Request
id_token_hint : The value of the id_token_hint parameter is the value of the id token that the application revokes.
The request to the logout endpoint also invalidates active session of NetSuite.