I usually just use the selfie camera on my phone. It's not perfect because it needs to be angled correctly and is a pain because you constantly need to be holding the phone, but it works well enough for me. I've also gotten good enough at my makeup now that I can do it without looking.

Maybe check out Molly Burke's youtube channel. You don't need to have vision to enjoy makeup and fashion.
Your mother might not have the same style as Molly but she can probably get some good tips from her videos.
I wish her luck!

The strongest I've ever (personally) seen has been 5X, although a quick check online indicates they do have stronger ones. I would have serious concerns once they go above 5X, though. Magnification cuts down on surface area, and small movements have big impacts, as well as distortions.

Depending on cost, there is another option that gets quite expensive. There is a model of CCTV called the Acrobat (https://www.enhancedvision.com/low-vision-product-line/acrobat-hd-ultra.html) that has a camera mounted onto a swivel, so you can turn the camera to your own face, and control with the remote. However, the cost is between $2-3K.