In the end of September 2017 Microsoft has announced a significant update to the scalability guidance for Exchange 2016.
If we knew till then that the maximum recommendation for memory was by 96 GB, Microsoft changed it now to 192 GB.
This effects of corse the Exchange Sizing Guidance, which you can find here and as well the EXC Requirement Calculator. The Calculator yo can download here.
The previously released guidance on maximum recommended cores and maximum memory size for Exchange 2013 is generally applicable to Exchange 2016 in terms of background and general scalability issues, however Microsoft has increased the recommended maximum memory size for currently supported versions of Exchange 2016 to 192GB.