Basically, like cub stages we would have Elder stages!
So for one, like when they reach 13 years old, they could be sitting up telling stories to npc's like the nursing cubs on a lioness.
And they wouldn't change much, but they would look like what we have now, just sitting up.

If that lion reaches 14 years old, they could be sitting back with an adolescent NPC.
Maybe watching something, and their leg bones may show more and have more face wrinkles and a tinge of white on the very tip of their muzzle.

And for 15 they may be with an adult NPC, as I said like the nursing cubs a lioness sees. And the elder would be on their stomach like a newborn cub.
They would be laying on the ground of course, but with their back legs tucked under them and front legs splayed out.

Tell me why you disagree if you do! :o And hopefully I posted it right haha!