  Event-by-event fluctuations of the charged particle multiplicity are studied
for a wide range of centralities for Au$-$Au collisions at $\sqrt{s_{NN}}$ =
200 GeV,
  Pb$-$Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV and 5.02 TeV using the
Pythia 8 Angantyr model. The centrality dependence of $\omega_{ch}$ observable,
which quantifies the fluctuations in terms of scaled variance is studied for
different pseudorapidity ranges and has been compared with those obtained from
a simple participant superposition model. The $\omega_{ch}$ was found to be
lower than the expectations from the participant model. The estimate would act
like a baseline for current and future measurements of event-by-event
fluctuations in the charged particle multiplicities in systems at LHC energies
where no de-confined medium of quarks and gluons are formed.
