How to properly extract Bootstrap theme settings for update?

Question

Bootstrap

Good day to all, the essence of the problem, there is a once bought theme for Bootstrap2, it was not possible to restore the acc to update at least under the 3rd version.
I set myself the goal of migrating the theme from the 2nd to the 4th version, the question is how to do it correctly.
Are there scripts/services capable of extracting theme settings from theme files? Well, or some other means ... I tried to compare the script and theme style with the standard Bootstrap2, but there were too many differences. Perhaps there are other directions of solution, instead of pulling out, some kind of auto-migration of one version to another ... let's say from 2nd to 3rd, then from 3rd to 4th or something else ... While I came across scripts for apa html, but I don't need html upnut and style and script themes.
Thanks in advance