If UCI got more applications this year (which they did, at 94,866), and if they accept fewer students than last year (which was 31,103), then obviously the acceptance rate will drop from last year’s figure of 36.6%.
If they accepted about 31,103 again, the acceptance rate would be about 33%. But that may be unlikely.
If they accepted only about 30,000, then the acceptance rate would be about 32%.
If they accepted only about 29,000, then the acceptance rate would be about 31%.
If they accepted only about 28,000, then the acceptance rate would be about 30%.
That last number would represent roughly a 10% decrease in accepted students relative to last year. Obviously the acceptance rate would continue to drop if they went even lower, but my guess is that this would be a less likely scenario.