how to setup a font family and font size for all elements in general

[lazarusA]

In Makie, you could do it in

fig = Figure(; fontsize = 24, fonts = (; regular= "CMU Serif"))

and then all subsequent block will use that.

Or by setting a theme with custom attributes.

[joa-quim]

OK, here is how it woks. This GMT man page shows all the defaults used by the program. We can change those defaults on a per directory bases by creating a gmt.conf file with gmtset but I think I deactivated that (by removing that) file in GMT.jl because it was too risky to inherit past temporary changes and forgetting it. We can, however, use the syntax shown in the gmtset man to make those changes valid only for a command (or a set of them) and from memory that change should be active until the next show command. The syntax is par=(name=value). See an example at roses.

There are themes in GMT.jl and I'm sure we can create new themes in GMT but not in top of my head on how practical the current situation is to create new ones from GMT.jl alone.