How can I implement proper software development lifecycle without access to source code?

Hi folks,

My company has an application from a vendor without the source code and it comes with an admin portal. We use the admin portal to make direct changes to fields in the database (think of this as the "code" change).

We would like to implement a way to have a proper software development "lifecycle" where changes to the database goes through approvals just like any normal code change and we can have the full history of changes.
We don't own have access to the source code from the vendor and any changes to the database through the admin portal cannot be tracked through traditional Git Flow.

Anyone can come up with an idea to have an approval-based process for such changes?