The McClarence Spacesuit and McClarence Helmet are given to the player during the quest "A Material World".

The McClarence Pack is given to the player during the quest "The Mock-a-teer".

Once these are unlocked, Jason McClarence will sell additional versions as part of his shop inventory.
The McClarence items support a large number of different skins, some of which are unlocked by completing quests or having certain additional content installed.
These skins are available immediately without any unlocks:

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This is unlocked by reaching "The Key" in the Crimson Fleet questline from the base game.

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This is unlocked by having the "Freestar Collective Settler" trait, or by becoming a Deputy near the start of the Freestar Collective questline from the base game.

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This is unlocked by accepting the job at Ryujin in the base game.

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This is unlocked by having the "United Colonies Native" trait, or by completing the quest "Supra et Ultra" from the base game.

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This is unlocked by completing the quest "Each Star a Stitch". This skin includes a unique particle effect reminiscent of the floating Caelumite particles found around temples, gravitational anomalies, and the caves artifacts are found in.

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This is unlocked by completing the quest from the "At Hell's Gate" Creation.

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This is unlocked by starting the questline in the "Watchtower" Creation.

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