S.H.I.E.L.D. certainly doesn’t seem to have helicarrier-level tech at this point, and that makes the contrast of power with the alien threat all the greater in this time period.
Thanks to Captain America: The First Avenger and Agent Carter, we know that S.H.I.E.L.D. has existed since World War II, but the Captain Marvel trailer gives us our first look at the agency in the 1990’s.
S.H.I.E.L.D. appears to be operating out of an Area 51-esque hidden basement where we see Nick Fury, along with another man, witnessing the dissection of what appears to be a Skrull.