HCS Armor in 2020?

is it possible to get the HCS armor set in 2020?

No

Isn’t that the armor that was only obtained by watching the HCS tournament on the Halo Channel a few years back?

Yep

It is still possible to get the HCS Weapon skins though.

If you buy some of the various Team Skin packs in the MS store, they’ll contain some weapon skins that aren’t ONLY the team ones, but also HCS ones too.
Take a look and read the descriptions.

If we get lucky, maybe HCS will do some giveaways for packs in the final tournaments they do this year for H5.