Hi, I have a 21.5" "iMac" now running Ghost 20.04, mostly running smoothly, the default MATE settings for the desktop were sane.

the graphics is intel:
vgapci0@pci0:0:2:0: class=0x030000 card=0x014f106b chip=0x16228086 rev=0x0a hdr=0x00
vendor = 'Intel Corporation'
device = 'Iris Pro Graphics 6200'
class = display
subclass = VGA

the display resolution is
VT(efifb): resolution 4096x2304

So for instance the default menubar of libre office and Virtualbox is almost unreadable as the text is about 2mm high and I am on the wrong side of 40.

I found a setting to increase the icon size on libreoffice, it is very kindegarten, but can at least be used, now virtualbox still has me reaching for a magnifying glass.

What should I be looking at to customise these menu sizes? what are the key words I need to use to google how to do it.

I had similar a few times when installing FreeBSD, and no routinely put :
Xft*dpi: 99
in my .Xdefaults file....

Also came across this in the Linux Mint forum, have a look, as it it's a Mate issue as well...
https://forums.linuxmint.com/viewtopic.php?t=136673