Ramesses II was a frail old man in his 90s, crippled with severe arthritis when he died, and still retains pretty much the exact same facial features, skin and hair intact.
Xin Zhui, on the other hand, looks nothing like she did in life, she was an attractive, wealthy, middle aged Chinese princess. Her body is now severely decayed and her facial features completely unrecognizable:
You are using circular arguments in which the life portraits are constructions of artists using the looks of their mummies to reconstruct what they may have looked like in life. We do NOT have photo quality images of either of them in life. Sorry, you are just wrong. Ramses the Great’s mummy is desiccated and highly discolored. Hers is not, it still evinces soft tissue with fat and skin color intact. That’s a huge difference.
The mummy of the princess has been somewhat depleted of water, but the skin, from what I’ve read, is still supple, and the subcutaneous fat cells are still present. The age of the princess at death is an estimate based on an examination of the body by forensic pathologists, not on contemporaneous records.
Ramses II is as hard and dry as an old saddle, brittle, and easily cracked. The estimate of his age is based on historic records from the period, compiled by knowing his age at ascension to the throne and his historic history as documented on stone walls. Again, a huge difference. We really do not know how robust his visage was at the time of his death. There are no realistic images of him, or unrealistic images for that matter, at that age.