You will need a high quality USB-C hub (powered) with both C and A connectors; avoid the ones that draw power from the USB connector on the laptop.
How many native USB C ports does the MB Pro 16 have? Ideally, you want the monitor on it's own dedicated USB port; not on the hub to avoid problems, so you will need at least 2 open connectors.
As to the monitor; it all depends on how exacting you plan to be with color space management. However, even a lot of mid-range monitors have color space compatibility well above sRGB nowdays.
In fact, the monitor you reference has, "Calman verified 3840 x 2160 resolution 4K display is factory calibrated for Delta E <2 accuracy, covering 99% of the DCI-P3 gamut".
That is pretty impressive for a sub $500 USD monitor and seems a good buy. In fact, it's way overkill if you intend to stay in sRGB color space, but nice to have if you decide to venture into larger color spaces.
Do you plan on profiling your scanner and your monitor or just settling for the factory calibration preset? If so, you will need a calibration puck and matching software, but maybe you don't want to go down that rabbit hole, which is very deep indeed...
Lastly, the VERY first thing I would do with an inherited laptop you are about to base your entire workflow around is take it to a good repair facility and have them clean it out thoroughly and replace the heat sink compound on the CPU!
Nothing like sinking an investment into a used computer only to have it fry after a few weeks due to bad thermal paste or a big hairball in the cooling system.