The $\lambda$ parameter as a function of source size $R$ extracted from the $\pi^\pm$K$^0_{\rm S}$ femtoscopy measurement in pp collisions at $\sqrt{s}=13$ TeV. Results are compared with the previous ALICE measurements, obtained from K$^0_{\rm S}$K$^0_{\rm S}$ and $\pi\pi$ femtoscopy studies in pp and Pb–Pb collisions and the calculations from a toy geometric model (see text). The modelcalculations for the tetraquark and diquark hypotheses for the K$^*_0(700)$ are shown as black and light green dashed lines, respectively,the short dashed lines representing the Gaussian $\rho(r)$ and the long dashed lines representing the exponential $\rho(r)$.