Plato himself has two levels of reality though he links them by some mysterious process called participation. Kant and Hegel also. But to Kant there was no bridge. To Hegel there is a bridge- dialectics which it seems he thought was a kind of group endeavor.
[Plato was forced into his opinion because of Parmenides. Kant was forced into his because of the problem that all character traits of things depend on the subject. That is Decartes, and also the problem between the rationalist and empiricists and the problem in his on home town between the Pietists and the school of the rationalists of Germany (Johann Salomo Semler,)]
The way Kant navigated between these two extremes was to find a ground of validity of each one, and thus one could know the limits of each one.