They're not included in the Season Pass.

Space Marine 2 is getting the first of a number of planned voice packs at the end of February, each sold for $4.99.

Warhammer 40k Space Marine 2 releases four trailers to show off the new Techmarine, and all my dreams have come true

This is not a drill, Warhammer 40k Space Marine 2 developer Focus Entertainment is showing off the new Techmarine class - ...
Bell of Lost Souls

Warhammer 40K: ‘Space Marine 2’s Techmarine Abilities Unveiled

Wanna know what those augmetics do? Focus has just revealed the upcoming Techmarine class abilities in detail.

Warhammer 40,000: Space Marine 2 - Official Techmarine's Omnissian Axe Gameplay Video

Space Marine 2 video to see the Techmarine's Omnissian Axe gameplay. The new Techmarine class is coming to Warhammer 40,000: Space Marine 2.
Bell of Lost Souls

Warhammer 40K: 4 Specialist Units For The Cult Chaos Space Marines We Need

The Big Four Chaos Space Marine Legions need some love. Here’s a few suggestions I have for Warhammer 40,000.

Warhammer 40,000: Space Marine 2 Is Deeply Discounted During A Great Time to Jump In

Year Anniversary Edition at Fanatical. Get the base game, both Season Passes, and jump in ahead of the new Techmarine class update.
IGN Africa

Warhammer 40,000: Space Marine 2's Upcoming Techmarine Class Has a Unique Ability That Has Fans Very Excited Indeed

Warhammer 40,000: Space Marine 2 will soon get the Techmarine, its seventh playable class, and with it comes a unique ability that sounds very exciting indeed.