Custom fields in webform membership renewal
Pinto Vasa, Welcome to CiviCRm SE. Yes its possible to include any CiviCRM custom fields on webform which is available under their respective tab of CiviCRM webform config setting. Those fields will be pre-populated on webform based on logged in user details, will be empty if its a anonymous submission or new submission if logged in. The webform can be used to populate details of specific contact by passing contact id (and checksum if the user doesn't have sufficient permission eg anonymous user or minimal permission authenticated user). 

eg http://example.org/renewmembership?cid=202&amp;cs=9f4a2e5d4d57567b6ba4468750ac128d_1585225559_168