  GRB 230307A is an extremely bright long duration GRB with an observed
gamma-ray fluence of $\gtrsim$3$\times$10$^{-3}$ erg cm$^{-2}$ (10-1000 keV),
second only to GRB 221009A. Despite its long duration, it is possibly
associated with a kilonova, thus resembling the case of GRB 211211A. In analogy
with GRB 211211A, we distinguish three phases in the prompt gamma-ray emission
of GRB 230307A: an initial short duration, spectrally soft emission; a main
long duration, spectrally hard burst; a temporally extended and spectrally soft
tail. We intepret the initial soft pulse as a bright precursor to the main
burst and compare its properties with models of precursors from compact binary
mergers. We find that to explain the brightness of GRB 230307A, a magnetar-like
($\gtrsim 10^{15}$ G) magnetic field should be retained by the progenitor
neutron star. Alternatively, in the post-merger scenario, the luminous
precursor could point to the formation of a rapidly rotating massive neutron
star.
