Based on @Cory 's reply I made a function that returns with the same date from the previous month. You just need datetime library:

from datetime import datetime, timedelta

def same_dt_in_prev_month(dt: datetime) -> datetime:
    orig_day = dt.day
    return (dt - timedelta(days=orig_day)).replace(day=orig_day)

one_month_ago = same_dt_in_prev_month(datetime.now())
print(one_month_ago)