Another option, depending on your use-case, you can increase the scale
factor as though your screen was HiDPI (or higher).
An easy way to test sizes is to open up a terminal and type:
GDK_SCALE=3 GDK_DPI_SCALE=1 mate-calculator
The first variable changes how much the interface is scaled. The second
variable changes how much the font DPI is scaled. You can play with
those values until the calculator (or whichever other program) looks
good, then you can lock those values by adding them to a ~/.xsession
file preceded by the export keyword:
export GDK_SCALE=3
export GDK_DPI_SCALE=1
This is effectively the same as setting the HiDPI option in mate-tweak,
but insted of 1 or 2, you get a lot more flexibility.