from datetime import datetime as dt
from datetime import timedelta
start_date = dt.strptime("2021-01-01", '%Y-%m-%d')
end_date = dt.strptime("2021-01-05", '%Y-%m-%d')
days = (end_date - start_date).days + 1 # +1は最終日を含めるため
date_list = []
for i in range(days):
date_list.append(start_date + timedelta(days=i))
for d in date_list:
print(d.strftime("%Y-%m-%d"))
# 2021-01-01
# 2021-01-02
# 2021-01-03
# 2021-01-04
# 2021-01-05