  We systematically study emergent Kondo lattice models from magic-angle
twisted bilayer graphene using the topological heavy fermion representation. At
the commensurate fillings, we demonstrate a series of symmetric strongly
correlated metallic states driven by the hybridization between a triangular
lattice of $SU(8)$ local moments and delocalized fermions. In particular, a
(fragile) topological Dirac Kondo semimetal can be realized, providing a
potential explanation for the symmetry-preserving correlated state at $\nu=0$.
We further investigate the stability of the Dirac Kondo semimetal by
constructing a quantum phase diagram showing the interplay between Kondo
hybridization and magnetic correlation. The destruction of Kondo hybridization
suggests that the magic-angle twisted bilayer graphene may be on the verge of a
solid-state quantum simulator for novel magnetic orders on a triangular
lattice. Experimental implications are also discussed.
