Hi & welcome! TY for the shout-out, Lin. :+)
With pairs of opposite leaves, it can't be a Kleinia/Senecio.
It looks like Crassula ovata to me. The older leaves look like they developed in a lot less light, causing them to curl and point down at the tips to expose more surface area to the lower light. Lower light can also contribute to larger than usual foliage on many plants, in attempt to capture more of the less intense light.
...and keep in mind that there are about 349 other species in Crassula genus. I've never seen most of them, and some are probably quite similar to C. ovata.