There aren't good tools here. You can use Xe/trace/distributed reply to gather a workload and replay it, but I'd do that against a test instance before applying patches.

Really you should have a set of tests that run items against the database with known results ot be sure things haven't changed. These could be used as unit/integration/system tests if you write code, or smoke tests against patches from a vendor, but you really need a sets of tests that apply to the things that matter in your environment.

For example, no sense in testing Service Broker if you don't use it. However, if you use CDC, then you should have some ways of testing that this is still working after any patch.