I am seeing some slow performance on a couple of my queries that run against my db2 on cloud instance. When I had a local db2, I would try these tools to see if I could improve performance. Now, with db2 on cloud, I believe I can run them using admin_cmd, however, if they are already being run automatically on my db objects, there is no point, but I am not sure how to tell.
As you stated, Db2 on Cloud is a managed (as a Service) database offering. But this is for the general part, not for application-specific stuff. Backup / restore can be done without any application insights, but creating indexes, running runstats or performing reorgs is application-specific.
Runstats can be invoked using admin_cmd. The same is true for running reorg on tables and indexes.