Increase your character’s total Hit Points by the number indicated for your class.
Using the Alchemist as an example, the number indicated by the class is 8 + the constituition modifier.
On HP gained from the class:
"To determine your character’s starting Hit Points, add
together the Hit Points they got when you chose their
ancestry and the amount listed in this entry, which
equals your Constitution modifier plus a fixed number.
Classes that intend for characters to rush into battle
with weapons bared gain a higher number of Hit Points
each level, while those for characters who cast spells or
engage in trickery gain fewer.
Each time your character gains a level, they increase their
maximum Hit Points by the amount listed in this entry.
For more about calculating your character’s Constitution
modifier and determining their Hit Points, see page 26."
Page 67-68
So, you still get CON modifier x level to HP.
All classes list X + CON as what they grant you in HP