I am not convinced that beauty is a steep cliff that you fall off of simply because you are past a certain age. Sure, people can become ill or frail or agéd at some point. But that varies by person and circumstances, and is not something I am interested in making blanket statements about....especially if such statements only apply to female actresses.
I recognize that youth and age look different from one another, and certainly I agree that many women working in Hollywood avail themselves of modern methods of preserving their appearances (though not all - Jamie Lee Curtis tries to stay away from all of that, apparently). But beauty is a lot more than sex appeal, and in the case of Lúthien, we are not talking about an actress who will be 'old' by any measure during these scenes. She's 33 now; we'll probably be finished with Lúthien in about 4 more seasons of Silm Film. So, I'm not sure exactly what the date will be, but likely about when she's approaching 40.
...and that's what I want Lúthien to look like at that age, not older, so we're good there. Makeup can be used to acheive the effects we're looking for, both with the age of the character and the effect of the silmaril on her appearance.
Somewhat amusingly, People
magazine has a "Beautiful" issue in which they feature 10 beautiful women who have been popular and achieved things over the past year. The women featured in this year's magazine range in age from 32 to 85, with only 3 of them being under the age of 40.
Get a first look at some of the women — Lizzo! Angela Bassett! Jane Fonda! Rihanna! — featured in PEOPLE's 2023 Beautiful Issue
"In Hollywood, there was a time when people believed that once an actress turns 40, it's over," [Angela Bassett] told InStyle.
"But no, those things that make us who we are — our sensuality, sexuality, compassion, and intelligence — that doesn't come to an end. It deepens and ripens, you know? It's all in the attitude."
A 19th century family I have easy access to photos of is the Martin and Guérin families; that is, the parents of St. Thérèse of Lisieux.
Here is her mother, St. Zélie Martin (nee Guérin):
I know the quality is not great, but it gives the ages, which is very helpful!
In the first 'young woman' photo, she is 25 years old (on the left). It was taken the year before she got married. 
Here is Zélie at 37 years old, holding one of her babies who would not survive the year 
Certainly, one could say that she's not looking great in the final photo, taken when she was 46 
Less than a year after this was taken, she died of breast cancer. She'd given birth to 9 children and buried 4 of them, one a 5 year old girl.
The hairstyle remains quite similar. No one seemed to smile much when they posed for photos at the time, so they tend to look rather severe. And of course it's in black and white. It was also common at the time to 'photoshop' waistlines in portraits like these; I don't know if this photo has been altered in that way. Given all of that, the aging effects are not easy to point out. But I did think it interesting that we have these snapshots a decade apart over the course of her life as an adult woman. There are numerous other photos of family members available, but it would take a bit of research on my part to date them all and figure out precise ages of the people in them at the time they were taken. So, these three photos will suffice for now.