Turbulent systems exhibit non-Gaussian, intermittent fluctuations at sub-inertial and inertial-range scales. Strong intermittency, often driven by coherent structures such as vortices and current sheets, is frequently observed in simulations and space observations, and is central to understanding turbulent energy dissipation and particle energization. High-order structure functions, particularly the third- and fourth-order central moments — skewness (S) and kurtosis (K) — provide tractable, partial quantification of non-Gaussianity. In hydrodynamic turbulence, S and K display well-established behaviors depending on the Reynolds number, and are theoretically predicted to asymptote to fixed values as scale approaches zero. Here, we aim to extend this framework to collisionless space plasmas by examining the scale-dependent S and K of magnetic field fluctuation increments. High-resolution in situ measurements at sub-ion inertial scales from Cluster and MMS reveal asymptotic behavior in both quantities, with occasional deviations at smaller scales that may be associated with wave interactions. Using intervals from the MMS unbiased campaign, we find that the estimated asymptotic values of S and K follow a power-law relationship, as predicted by hydrodynamic turbulence. Complementary analyses of 3D MHD and 2.5D PIC simulations are performed to investigate how the behavior of S and K connects fluid and collisionless regimes.