Hi Garinas,
I am Sumit, an Independent Advisor and a 2-Year Windows Insider MVP here to help.
Sorry, but you cannot increase the time for vault as this is by design.
https://support.office.com/en-us/article/protec...
Personal Vault automatically locks after a period of inactivity (20 minutes on the web, 3 minutes on a mobile app) and then you need to unlock it to get at your files again. All your documents, photos, and videos in Personal Vault are easy to access from onedrive.com, your PC, or other capable devices.
As we are just volunteers here trying to help, you may add a Feedback in Onedrive uservoice:
Feature Suggestions for Microsoft OneDrive
https://onedrive.uservoice.com
Hope that helps.