For PFAS, yes, definitely. They've done studies on this, some are linked elsewhere in the thread. PFAS in the bloodstream is removed through either whole blood or plasma donation.

For microplastics, I can't say with absolute certainty, as I don't know the concentration of microplastics in the blood, or if replacement blood/plasma contains microplastics. But, the mechanism is the same: extract polluted fluids; allow body to replace with non-polluted fluids. Concentration of pollution falls.