  Charged lepton flavor violation (cLFV) processes, potentially important for
various Beyond the Standard Model Physics scenarios are analyzed in the
Standard Model Effective Field Theory (SMEFT) framework. We consider the most
relevant 2 quark-2 lepton $(2q2\ell)$ operators for the leptonic and
semi-leptonic LFV B-decay (LFVBD) processes $B_s\to \mu^+e^- , B^+\to
K^+\mu^+e^-, B^0\to K^{*0}\mu^+ e^-, {\rm and}~ B_s\to \phi\mu^-e^+$. We
analyse the interplay among the Wilson coefficients responsible for these
LFVBDs and other cLFV processes like $\rm CR (\mu\to e)$, $\ell_i \to \ell_j
\gamma$, $\ell_i \to\ell_j\ell_k\ell_m$ and $Z \to \ell_i \ell_j$, to find the
maximal possible LFV effects in $B$-meson decays. We probe the scale of new
physics in relation to the constraints imposed by both classes of the LFV
decays while considering both the present bounds and future expectations. In
view of proposed experiments at LHCb-II and Belle II to study charged LFV
processes, we have also provided the upper limits on the indirect constraints
on such LFVBDs. For the processes where $B$ meson is decaying to $\mu^{\pm}$
and $e^{\mp}$, we show that new physics can be constrained by an enhancement of
2-4 orders of magnitude on the current sensitivities of the BRs of $B^+\to
K^+\mu^+e^-, B^0\to K^{*0}\mu^+ e^- {\rm and}~ B_s\to\phi\mu^{\pm}e^{\mp}$.
