방법
from datetime import datetime
from dateutil.relativedelta import relativedelta
# 2년 반 후
two_and_half_later = datetime.strptime("2023.01.01", "%Y.%m.%d") + relativedelta(years=2, months=6, days=-1)
print(two_and_half_later)
# => 2025-06-30 00:00:00