I would lean towards 32GB if you can reasonably fit it in the budget without sacrificing in other key areas. You can get by with 16GB, but it depends on the complexity/layers/resolution of the projects, and how much multitasking she's doing. It's better to have the headroom and a bit of a hedge against future software demands (futureproofing), in my opinion, even if it ends up being more than she needs.
I'm not a pro, but I do use a lot of the apps in the Creative suite, and also looking to learn 3D modeling programs and opted to go for 32GB for my in-progress Ryzen 3000 (still waiting for backordered 3700X to ship) build. I'm not sure how finicky the RAM will be, though, because 16GB modules won't necessarily run at the rated (technically overclocked) speed. But I'm willing to potentially sacrifice a little clock speed and loosening the timings for the increase.
16GB has been sufficient for me for gaming, VR, Premiere, Photoshop, etc in the past, but I've had to eye my memory usage on occasion, especially when multitasking. I've wanted to be at 32GB or more since I also use VMs/containers (Docker) on occasion, but the pricing when doing a new build or my budget didn't allow me to do so. I think memory prices now are semi-reasonable, so I feel better about getting potentially more RAM than I need than saying "I can upgrade later if I need to", which with only two slots - both going to be occupied - really means buying a new set of RAM. It's about peace of mind more than anything.
The general consensus I've seen as far as RAM for pro usage has always been "get as much RAM as you can afford", and that more cores/threads you have the more memory you'll want to have (not a hard and fast rule by any means, and applies more to server and HEDT threadcounts where you are "feeding" a lot of threads).
Also, a NVMe SSD should mitigate the slowdown
somewhat if the system does run out of memory during rendering and is forced to use the swap disk/page file. Those new PCIe 4.0 drives might be interesting choice given nearly 5,000 MB/s write speeds, though other NVMe drives are still plenty fast, and you should definitely opt for NVMe regardless (m.2 form factor also saves on space and cabling vs SATA in an ITX build).
These are my specs, about 2-3 weeks away from completion as I'm waiting on parts to arrive. May be able to test open-air or on a test bench, though, within a week (I'll do some testing and may post relevant benchmarks if it helps). Picked parts based on mixed workstation use, but also chosen to be good for gaming; I would choose a different monitor for pure rendering work. I, too, ruled out the Shift early on because it has too many potential problems (though the new mesh panels means its on my radar for future build).
Chose some brands over others based on reliability (admittedly somewhat anecdotal), but overall tried to optimize for performance while accounting for thermals and price: I wanted to throw in a 2080Ti in, for instance, and toyed with going for the 3900X, but ultimately decided to be more conservative given the potential for more noise and heat with the beastlier parts. I also chose not to use liquid cooling because while the major AIOs are reliable enough now, they can still be problematic in the rare instance of a pump failure or leaks. When a liquid cooler fails, it can kill other parts; when a air cooler fails, it just turns into a potentially-insufficient-but-harmless heatsink. I had a Enermax Liqtech 360 on my 1950X that thankfully never failed in over a year of usage, but a lot of people
had problems with it, and since then my preference has gone back to air wherever possible, and since the best air coolers rival low and mid range AIOs, that's not too hard to do most of the time.
Case: Sliger SM580
CPU: Ryzen 3700X
Motherboard: GIGABYTE X570 I AORUS PRO
RAM: G.SKILL TridentZ RGB Series 32GB (2 x 16GB) 288-Pin DDR4 SDRAM DDR4 4000*
Cooler: Noctua NH-L9i
GPU: ZOTAC 2070 Mini**
PSU: Seasonic FOCUS SGX-650
SSD: Intel 760p Series M.2 2280 1TB PCIe NVMe 3.1 x4***
Monitor: Alienware 34" 1440p G-sync 100Hz (120Hz overclocked) Curved Monitor AW3418DW
Case Fans: 4x Noctua NF-A14 (140mm)
Thermal Paste: Noctua NT-H2
* unnecessary speed and expense given the capacity and "sweet spot" for Ryzen 3000 being 3600 or 3733MHz - will likely tighten timings and have to drop frequency. Opted for it since I often swap parts between builds, and it may end up in an Intel build or future AMD build that can take advantage of it.
** could have gone with super or other larger card as there is room for it in the case, but I like to have airflow as unimpeded as possible in the case, and for a portable ITX build the smaller and lighter the parts, the better
*** I'm getting a NAS, otherwise I might have went for 2TB or added another drive for extra storage
EDIT: This is a good article with specifications advice, though hasn't been updated for Ryzen 3000 and GTX Super launches.
Best Computers & Workstations in different Tier Builds for 3D Modeling and Rendering, CPU Rendering & GPU Rendering
www.cgdirector.com