The Panda's point of view is the same when walking, and when he sits while eating.
(in spectator mode if you are spectating the mob)

What I expected to happen was...:
The panda's POV in spectator mode would be different in height when he is sitting.

What actually happened was...:
The panda's POV is the same exact height when he is sitting and walking on foot.

Steps to Reproduce:
1. Spawn a panda
2. switch to spectator mode
3. see that the panda's height is low (okay, that is correct, however see the next step)
4. switch back to survival, and feed the panda with bamboo. Now, he is eating
5. switch to spectator and left click him to spectate the mob.
6. See that the height is the same