Even the Intel 13" can be configured and ordered with a max 64GB DDR4 RAM for a total of $240, so am sure that the 16" would be configurable with at least that much.
AMD can be configure for 64GB DDR5 for $320.
Again, that is total $240 for 64GB RAM. Apple charges $800 to upgrade from 16GB to 64GB.
RAM can also be purchased separately from the marketplace[0], or from a retailer of your choice, if cheaper.
thank you! just surprised it's not right there as a spec on the page for the 16" which clearly would be for power users. So many laptops max out at 32g or even 16g.
It's been a revelation having 64gb in my Macbook, I never want to go back.