3D visualisations of magnetic and thermodynamic structures in the three simulations: Ref (top), By200 (middle), and By800 (bottom), shown during their quasi-static phases at t = 324 min. The corrugated horizontal surface marks the τ₅₀₀ = 1 layer, coloured by the vertical magnetic field B_z. The vertical side panels show the convective velocity v_z in the upper convection zone, while magnetic field lines, seeded from a uniform 15 × 15 grid at z = 3 Mm, are coloured by temperature. This transitions from pink in the chromospheric temperature minimum (∼4000 K), to white in the TR (∼40 000 K), and green in the low corona (∼500 000 K). The panels illustrate the progressive emergence of horizontal flux, from the nearly vertical, coronal-hole-like topology of Ref, through loop-dominated By200, to the strongly inclined, horizontally dominated configuration of By800. Associated movies are available online.