Semiconductor moir\'e superlattices have been shown to host a wide array of
interaction-driven ground states. However, twisted homobilayers have been
difficult to study in the limit of large moir\'e wavelength, where interactions
are most dominant, and despite numerous predictions of nontrivial topology in
these homobilayers, experimental evidence has remained elusive. Here, we
conduct local electronic compressibility measurements of twisted bilayer
WSe2​ at small twist angles. We demonstrate multiple topological bands which
host a series of Chern insulators at zero magnetic field near a 'magic angle'
around 1.23∘. Using a locally applied electric field, we induce a
topological quantum phase transition at one hole per moir\'e unit cell.
Furthermore, by measuring at a variety of local twist angles, we characterize
how the interacting ground states of the underlying honeycomb superlattice
depend on the size of the moir\'e unit cell. Our work establishes the
topological phase diagram of a generalized Kane-Mele-Hubbard model in tWSe2​,
demonstrating a tunable platform for strongly correlated topological phases