Excel: Is it possible to add X cells for a specific date and when the date changes (on its own column) then add the next Y cells below that new date

Question

I have an excel sheet with a simple sum fuction, but I want that fuction to work for all the products on a specific date. E.x Lets say that on 14/12/2021 I received 20 products each one with different size. I want the add fuction to add all the sizes together on that date and create a number but when the new shipment comes on e.x 25/01/2022 I need the add fuction to add the products after that date and ignore the products and their sizes before that date. Is something like that possible ? Thank you in advance for the enlightening

Sample: sample image I need basicaly in every different date the sizes of the products (how many small medium large items etc) that are next to that date to be added and get a result for each shipment

Answer 1

So if I understand right... Every row has several columns that should be summed. Sometimes several rows have the same date then all rows and columns with the same date should be summed.

=SUM(C2:D2)
=SUMIFS(E:E,A:A,A2)