It would essentially do the same job as a modern G-suit. For example, the suit for the Eurofighter Typhoon compresses the legs and arms already (and possibly the lower torso, can’t quite remember). That only leaves the area around the lungs, and the head, unpressurised by the suit, and compressing those isn’t desirable anyway if you want to continue to breathe and stay conscious.
Liquids (I know you said fluids, but as G-suits already use gas I’ve assumed liquids) are also a lot heavier than air (and air can be drawn in from outside the aircraft constantly), so that’s just extra weight that isn’t needed on an aircraft.
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