sql server 2016 sp1 to sp2 with latest cumulative
Do I then install the last cumulative?

Yes, you should install the latest cumulative update.  Some folks would advise to install the &quot;next to latest&quot; version.  Since the latest one just came out 2 days ago at the time of this writing, it might be prudent to wait and see if any issues arise before going there.

Are there any tools that would help me check what issues may come up after this update.

There's not a tool I'm aware of.  You basically need to go through the KB articles for each update if you want to see what's included.  And check the KB for the CU you're installing specifically to see if there are any &quot;known issues&quot; with that version.  Here are the KB articles for SQL Server 2016 releases: SQL Server 2016 build versions
You can also follow the SQL Server blog, which will notify you of new releases, and also if there are significant issues with a release or if one gets pulled back entirely.