  We report the first detection of evolving Low-Frequency Quasi-periodic
Oscillation (LFQPO) frequencies in hard X-rays upto $100$ keV with
$AstroSat/LAXPC$ during `unusual' outburst phase of Swift J1727.8-1613 in
hard-intermediate state (HIMS). The observed LFQPO in $20 - 100$ keV has a
centroid $\nu_{_{\rm QPO}}=1.43$ Hz, a coherence factor $Q= 7.14$ and an
amplitude ${\rm rms_{_{\rm QPO}}} = 10.95\%$ with significance $\sigma = 5.46$.
Type-C QPOs ($1.09-2.6$ Hz) are found to evolve monotonically during HIMS of
the outburst with clear detection in hard X-rays ($80 - 100$ keV), where ${\rm
rms_{_{\rm QPO}}}$ decreases ($\sim 12-3\%$) with energy. Further, $\nu_{_{\rm
QPO}}$ is seen to correlate (anti-correlate) with low (high) energy flux in
$2-20$ keV ($15-50$ keV). Wide-band ($0.7 - 40$ keV) energy spectrum of
$NICER/XTI$ and $AstroSat/LAXPC$ is satisfactorily described by the `dominant'
thermal Comptonization contribution ($\sim 88\%$) in presence of a `weak'
signature of disk emissions ($kT_{\rm in} \sim 0.36$ keV) indicating the harder
spectral distribution. Considering source mass $M_{\rm BH}=10M_\odot$ and
distance $1.5 < {\rm d~(kpc)} < 5$, the unabsorbed bolometric luminosity is
estimated as $\sim 0.03-0.92\%L_{\rm Edd}$. Finally, we discuss the
implications of our findings in the context of accretion dynamics around black
hole X-ray binaries.
