Extracted source size $r_\text{core}$ of primordial $\ppiPlus$ pairs as a function of the pair transverse mass. The results are compared with the $r_\text{core}$ extracted from p--p pairs  as well as $\uppi^\pm$--$\uppi^\pm$ and $\text{p--}\text{K}^+$ pairs  in HM pp collisions at $\sqrt{s}=13$ TeV by ALICE. The lines (boxes) show the statistical (systematic) uncertainties. The gray band represents the extrapolated scaling of p--p pairs .