explain
SELECT extract(month from "blog_userSession"."access_dt") AS "mm"
,      extract(day from "blog_userSession"."access_dt") AS "dd"
,      COUNT(*) AS "cnt"
FROM "blog_userSession"
WHERE "blog_userSession"."access_dt" > TO_TIMESTAMP('2022-06-01 00:00:00', 'YYYY-MM-DD HH24:MI:SS')
GROUP BY extract(month from "blog_userSession"."access_dt")
       , extract(day from "blog_userSession"."access_dt")
;

explain (ANALYZE, BUFFERS)
SELECT extract(month from "blog_userSession"."access_dt") AS "mm"
,      extract(day from "blog_userSession"."access_dt") AS "dd"
,      COUNT(*) AS "cnt"
FROM "blog_userSession"
WHERE "blog_userSession"."access_dt" > TO_TIMESTAMP('2022-06-01 00:00:00', 'YYYY-MM-DD HH24:MI:SS')
GROUP BY extract(month from "blog_userSession"."access_dt")
       , extract(day from "blog_userSession"."access_dt")
;

https://www.postgresql.org/docs/12/using-explain.html