Supplemental Material for "High-topological-number skyrmions with tunable diameters in two-dimensional frustrated J1-J2 magnets

1.The mechanism of frustration interactions in an hexagonal close-packed (HCP) lattice; 2.The magnetic phase diagram of J1-J2 under different Q; 3.The influence of dipole-dipole interaction (DDI) on the skyrmion phase diagram; 4.The influence of different supercell sizes on the skyrmion spin textures; 5.The manipulation of the skyrmion size via J, K, and B; 6.The spin textures of skyrmions with high Q under increasing magnetic fields; 7.The intrinsic properties of the CoCl2 monolayer.