  Diverse emergent correlated electron phenomena have been observed in twisted
graphene layers due to electronic interactions with the moir\'e superlattice
potential. Many electronic structure predictions have been reported exploring
this new field, but with few momentum-resolved electronic structure
measurements to test them. Here we use angle-resolved photoemission
spectroscopy (ARPES) to study the twist-dependent ($1^\circ < \theta <
8^\circ$) electronic band structure of few-layer graphenes, including twisted
bilayer, monolayer-on-bilayer, and double-bilayer graphene (tDBG). Direct
comparison is made between experiment and theory, using a hybrid
$\textbf{k}\cdot\textbf{p}$ model for interlayer coupling and implementing
photon-energy-dependent phase shifts for photo-electrons from consecutive
layers to simulate ARPES spectra. Quantitative agreement between experiment and
theory is found across twist angles, stacking geometries, and back-gate
voltages, validating the models and revealing displacement field induced gap
openings in twisted graphenes. However, for tDBG at $\theta=1.5\pm0.2^\circ$,
close to the predicted magic-angle of $\theta=1.3^\circ$, a flat band is found
near the Fermi-level with measured bandwidth of $E_w = 31\pm5$ meV. Analysis of
the gap between the flat band and the next valence band shows significant
deviations between experiment ($\Delta_h=46\pm5$meV) and the theoretical model
($\Delta_h=5$meV), indicative of the importance of lattice relaxation in this
regime.
