How to do multichannel ADC data logging
In the 6.5 digit multimeter level of measurement (around 27 bits of resolution) It falls under the name "Data Acquisition Unit"

Things like the Keithley DAQ6510 which for the 80 channel (I think most of which can be measured differentially) is about $1800 US, note that in most of these systems the switching cards are actual relays, as such they do have a number of cycles before there performance degrades (something around 10 million cycles usually)

There are cheaper alternatives, but the switching will be your issue, silicon switching at that level of precision is extremely hard, non-linear with voltage and non-linear with temperature,

This is making an assumption about the resolution your after based on the devices sold in you link, if your resolution requirements are something like 12 bit at a reasonable voltage, then mux chips can come back in to play,