You can have a look at NDWI (Gao, 1996), which is the index of Sentinel-2 bands 8A and 11. The best spatial resolution you will get with Sentinel-3 is 300m (https://sentinel.esa.int/web/sentinel/user-guides/sentinel-3-olci/resolutions)

See these links:
MONITORING CROP FIELD SOIL MOISTURE (NDWI) USING SENTINEL-2 TEMPORAL SERIES

Normalized Difference Water Index

Thanks a lot, I was looking for some kind of similar product for analysis on where and when are parcels being irrigated. Thought about the Moisture Index product, downloadable from EO browser. Do you think that is a good indicator to represent when and where a parcel is being irrigated in dry seasons? Thanks in advance