As far as I've seen from self-hosting, there's no caching layer setup. It comprises of the following:
- Postgres DB
- PostgREST REST API
- Auth
- Storage
- PG Meta
- Kong (routing)
- Realtime
- Studio (dashboard)
Unless the hosted/managed projects do something differently, then they don't implement any caching.
You could certainly host your own Redis instance somewhere and use that as a cache. Alternatively, it might be possible to use pg_cron and some dedicated caching tables to implement a similar system