There are many open source (and even more proprietary) pg_stat_statements forks that allow you to view query execution plans:

pg_state_plans https://github.com/2ndQuadrant/pg_stat_plans pg_store_planes https://github.com/ossc-db/pg_store_plans pg_stat_monitor https://github.com/percona/pg_stat_monitor

All of them did not suit me in some way and I wrote my own https://github.com/postgredients/pg_stat_query_plans. I'll tell you why and how, and what I would like to add to the original pg_stat_statements so that my extension is not will be needed.