No, they do not get reach.
They would be Large (Long) which is most quadrupeds. Table 9-1 shows Large (Long) have a 5' reach. Reference is p474.
"Table 9–1 also lists the typical reach for creatures of each
size, for both tall creatures (most bipeds) and long creatures
(most quadrupeds). See page 455 for more about reach."
This is confirmed in the Bestiary with a Grizzly Bear (large) not having reach with a claw while a Hill Giant (large) does have reach with a fist
Even in PF1e, reach for animal companions seemed a bit rare, and even notable. If I remember right, only a few of them, such as gorrillas and some carnivourous dinosaurs seemed to get it just based of bodyshape/size.
I am sure there were a few with specifically increased reach too, but none of them immediately come to mind. Paizo might release a few creatures like that in this edition, but it will likely not be that common since reach is less important for most creatures now.