How do you approach upgrading Angular across major versions?

Show that you treat it as routine maintenance rather than a project, because that is the only approach that works long term.

• Upgrade one major version at a time, using ng update. Angular ships schematics that rewrite most breaking changes automatically, but only for a single-version step.
• Read the update guide at update.angular.io for your exact from-and-to versions before starting. It lists what the schematics will not handle.
• Get the test suite green first. Without tests, an upgrade is a leap of faith.
• Handle third-party libraries separately. These are usually the real blocker — a library that has not released a compatible version can stop the whole upgrade, so check them before you begin.
• Keep the upgrade on its own branch with no feature work mixed in, so a rollback is clean.

Note: The strongest thing to say is that you would upgrade on a cadence — every release, or every other one. Teams that fall four versions behind end up doing a rewrite instead of an upgrade, and interviewers have usually lived through that.