An SSD can compensate for limited RAM, but is by no means a direct replacement.
Plenty of RAM means you can have more (and larger) programs open and still have the system switch between them immediately without perceptible delay.
Reducing the amount of RAM will mean that programs either get pushed out to the swap file or you have less of them open at once. An SSD might be faster than a HDD for switching back to paged out tasks, but by no means will it be as fast as having actual RAM.
An NVMe SSD might be able to read at up to 3GB/s, but modern RAM set up in dual channel on an up to date processor can do up to 30GB/s. A SATA SSD might manage up to 500MB/s. There are worlds of difference between the three things.
An SSD can make a memory starved system usable but it is still limiting what you can do by not being able to keep everything in RAM. It is better than running off an HDD at the very least.