GNUplot command to produce tex files with 12pt font size?

I am using GNUplot in combination with the TikZ terminal by using the command 'set term TikZ standalone color solid size 3.25in,2.25in'.

The first line in `.tex` file that is produced when running `'gnuplot <filename>'` is always `\documentclass[10pt]{article}`, while I need it to be 12pt.

I know I can simply change the 10pt to 12pt manually but then often locations of text labels do not look nice any more.

Thus, I want to know which command I have to denote in the GNUplot script to inherently make the fonts 12pt, so that the text labels are placed correctly by GNUplot itself.

The `<fontdesc>` string may contain any valid TeX/LaTeX/ConTeXt font commands like e.g. `\small`. It is passed directly as a node parameter in form of `"font={<fontdesc>}"`. This can be ’misused’ to add further code to a node, e.g. `\small,yshift=1ex` or `,yshift=1ex` are also valid while the latter does not change the current font settings. One exception is the second argument of the list. If it is a number of the form `<number>{unit}` it will be interpreted as a fontsize like in other terminals and will be appended to the first argument. If the unit is omitted the value is interpreted as ’pt’. As an example the string `\sffamily,12,fill=red` sets the font to LaTeX’s sans serif font at a size of 12pt and red background color. The same applies to ConTeXt, e.g. `\switchtobodyfont[iwona],10` changes the font to Iwona at a size of 10pt. Plain TeX users have to change the font size explicitly within the first argument. The second should be set to the same value to get proper scaling of text boxes.
So your gnuplot header should became `set term tikz standalone color solid size 3.25in,2.25in font ",12"`.