Multilooking of S-1 GRD

Do S-1 GRD data need multilooking processing?

No that is not mandatory.

thank you very much!

Thank you very much!

Has the S-1 GRD data been multilooking?

please refer for the technical description of Level-1 GRD products
https://sentinel.esa.int/web/sentinel/technical-guides/sentinel-1-sar/products-algorithms/level-1-algorithms/ground-range-detected

Thank you very much