Postgres 9.6 (pgAdmin 4) - How to query daily statistics
The extension pg_stat_statements is what you are looking for.  It is not provided by PgAdmin4, but you can use PgAdmin4 to read from the view it creates.  It provides cumulative stats, so you either need to reset them every night, or just save daily snapshots and compute the differences.  You might want to use PgAgent to automate some of this.  (I have no experience with PgAgent, I just know that it exists.  I use crontab to schedule things)