I have a 2019 27“ iMac and it feels like an entirely new way of working. The swap file is of course ridiculously small (about 300 MB) since all the used memory can stay in the RAM. That also means less writing on the SSD and longer longevity. Also less performance demands because less rewriting is needed.
Doing some light developing and medium browsing, my RAM is usually at around 28-34 GB of usage.
In the light of this, 64 GB would already have bren enough, but I will do some more demanding programming in the coming months so I am happy I maxed it out. I bought a 128 GB set from OWC I believe which was tagged at around 200-300 €, which was fair. I would have had to pay over 1000 for half of that from Apple just so I didn‘t have to open the hatch.
Now they are smarter, they soldered the ram and solid state so they can