  We study the timing and spectral properties of the X-ray pulsar 2S 1553--542
using the NuSTAR, and NICER during the outburst in January--February 2021.
During the outburst, the spin period of the neutron star was 9.2822 s based on
NuSTAR data. The pulse profiles are studied using different NICER observations,
which implies that the profile is more or less sinusoidal with a single peak
and the beaming patterns are mostly dominated by the pencil beam. The NICER
spectra of the source are studied for different days of the outburst and can be
well described by a model consisting of a blackbody emission and power law
along with a photoelectric absorption component. The variation of spectral
parameters with luminosity is studied over the outburst. The photon index shows
anti-correlation with luminosity below the critical luminosity, which implies
that the source was accreting in the sub-critical accretion regime during the
NICER observations. We also report the anti-correlation between pulsed fraction
(PF) and luminosity of the 2S 1553--542 using NICER observations. The evolution
of spin-up rate with luminosity is studied during the outburst, which implies
that both are strongly correlated. The torque-luminosity model is applied to
estimate the magnetic field at different spin-up rates. The magnetic field is
estimated to be 2.56 $\times 10^{12}$ G from the torque-luminosity model using
the source distance of 20 kpc. The magnetic field is also estimated using the
critical luminosity, which is also consistent with our findings.
