A measurement of the substructure of bottom quark jets (b jets) in proton-proton (pp) collisions is presented. The measurement uses data collected in pp collisions at $\sqrt{s}$ = 5.02 TeV recorded by the CMS experiment in 2017, corresponding to an integrated luminosity of 301 pb$^{-1}$. The soft-drop-groomed jet radius, $R_{g}$, and momentum balance, $z_{g}$, of b quark jets are presented. These observables can be used to test perturbative quantum chromodynamics predictions that account for mass effects. An algorithm to identify and cluster the charged decay daughters of b hadrons is developed for this analysis, which facilitates the exposure of the gluon radiation pattern of b jets using iterative Cambridge--Aachen declustering. Because the b hadron is partially reconstructed from its charged decay daughters, only charged particles are used for the jet substructure studies. In addition, a jet fragmentation function, $z_{b,ch}$, is measured, which is defined as the distribution of the ratio of the transverse momentum ($p_{T}$) of the partially reconstructed b hadron with respect to the charged-particle component of the jet $p_{T}$. The measured distributions are unfolded to the charged-particle level. The b jet substructure is compared to that of inclusive jets, which are dominated by light-quark and gluon jets, to assess the role of the b quark mass. A strong suppression of emissions at small $R_{g}$ values is observed for b jets when compared to inclusive jets, consistent with the dead-cone effect. The measurements are also compared with theoretical predictions from Monte Carlo event generators. This is the first b jet substructure study that clusters together the b hadron decay daughters.