  4U 1543--47 is one of a handful of known black hole candidates located in the
Milky Way Galaxy, and has undergone a very bright outburst in 2021, reaching a
total of $\sim$9 Crab, as observed by the Monitor of All-sky Image (MAXI), and
exceeding twice its Eddington luminosity. The unprecedented bright outburst of
4U 1543--47 provides a unique opportunity to test the behavior of accretion
disk models at high luminosities and accretion rates. In addition, we explore
the possibility of constraining the spin of the source at high accretion rates,
given that previous spin measurements of 4U 1543--47 have been largely
inconsistent with each other. We measure the spectral evolution of the source
throughout its outburst as observed by Insight-HXMT, and compare the behavior
of both the thin disk model kerrbb2, as well as the slim disk model slimbh up
to the Eddington limit for two different values of disk $\alpha$-viscosity. In
addition, given the behavior of these two models, we identify two `golden'
epochs for which it is most suitable to measure the spin with continuum
fitting.
