In DND, Rakshasa are portrayed as fiends with the heads of wild cats. In the Hindu myths, they’re portrayed more visually human but taller, more muscular, with fangs and tusks. , and an appetite for human flesh. I’m getting the idea that they are more related to the European ogre. However, I don’t know where dnd got the idea of them being feline.
It’s DnD. They don’t go for accuracy, they go for whatever the creator thinks would be pretty cool. That’s really all there is to it.
Based on the Ramayana, I’d say they have more in common with dragons of medieval lore.
They are also a mob in the mmorpg Perfect world international. They can be found in the Morai map, though it’s been years since I read the lore, they looked like your description of the Hindu myth, and it’s a Chinese game that gets translated to English. It’s basically a humanoid figure in robes, with the features you described.
I relate them more to cannibals lol.