I am building an ITX PC which I intend to drive for as long as possible so I am stuck in the same dilemma; whether to go 32 GB or save a buck with 16 GB.
When I built my last machine in 2011, I had a 2×4 GB DDR3 combo which was adequate till 2017. I started contemplating adding another 8 GB as I experienced functional restrictions but since DDR4 had become the norm, it was impossible to buy an 8 GB kit at a reasonable cost.
If I go the 32 GB route today, I'll end up spending ₹6200 for the additional 16 GB which seems an overkill but it will be useful if I intend to use the PC longer.
Of course, 16 GB will suffice you in the coming years but the next upgrade will be a total revamp of the core components and they are always more expensive than a RAM stick.
I've never felt that I had tremendous gains from a CPU or Motherboard upgrade when compared to a HDD to SSD, 8GB to 16 GB RAM or newer GPU version.
So, unless you are absolutely sure to upgrade the CPU, Motherboard and RAM in the coming 3 years, stick with 16 GB. Else, get the 32 GB and delay your upgrade date. I feel, I'm better off spending the money later on extra monitor, GPU, storage or software services instead of spending again on core components whose cost rises with time.
A good processor (5600x 6c12t) today costs ₹27,000 but when I built my system, I spent around ₹9000 on an i5 2500 4c4t. Both of them are good mid-range processors of their time but the cost of a good mid range processor has risen a lot faster than the cost of a higher capacity RAM. You can expect a good processor to cost over 30k in 3 years but you might end spending the same amount of money by today's standards on RAM but a higher capacity stick.
Also, you also never know what might interest you later (VM in my case) that might need the extra RAM.