Expanded Octet Rule and Coordination Compounds

[Nisarg Shah 1C]

I do not understand how nickel can be a central atom of a coordination compound and form 10 coordinate covalent bonds with other ligands. I thought Nickel is only allowed to have 18 valence electrons with an expanded octet (2 electrons from s, 6 from p, and 10 from d). Do the central atoms in coordination compounds not follow the octet/expanded octet rule? And if they don't, why is this possible?

[Tanaisha Italia 1B]

I think that because Nickel has two electrons from the 4s subshell and 8 electrons from 3d, it can form 10 bonds in a coordination compound. It is similar to how Sulphur can form 6 bonds (2 electrons in 3s + 4 electrons in 3p) due to the expanded octet rule and its empty d-orbitals.