The $\pi^\pm\pi^\pm$ experimental correlation functions (green solid circles) as function of the invariant pair relative momentum $q_\mathrm{inv}$ in pp collisions at $\sqrt{s}=13$ TeV for the raw multiplicity $N_{\rm trk}$ intervals of (1--18), (19--30), and ($>30$) in the (0.15--0.3) GeV/$c$, (0.3--0.5) GeV/$c$, (0.5--0.7) GeV$/c$, (0.7--0.9) GeV$/c$ and (0.9--1.2) GeV$/c$ $k_{\rm T}$ intervals. A sphericity selection of $S_{\rm T} < 0.3$ is applied. The data are compared with PYTHIA 8 calculations shown by blue crosses. The error bars represent the statistical uncertainties, while the systematic uncertainties are negligible.