Customize number chapter size in ConTeXt

Question

I want to control the size of the chapter number in ConTeXt with some command like LaTeX \anyfontsize. I was checking this answer https://tex.stackexchange.com/a/668592/14423 I was able to modify the gap between the chapter number and the vertical line (\blackrule) but I could not control the size of the chapter number. Another related question is, the size of \blackrule is affected by the size of the chapter number?

\definehspace[oneem][-.125 em]
\starttexdefinition MyNumberChapterCommand #1
    {\tfe #1}
    %\enspace
    \hspace[oneem]
    \blackrule[
        height=\lineheight,
        depth=\strutdepth,
        width=2pt,
        color=darkred,
    ]
\stoptexdefinition
\definebodyfont[14pt][rm][tfe=Regular at 36pt]
\setuphead[chapter][
    numbercommand=\MyNumberChapterCommand,
    page=no,%Just to have them on the same page here

    %numberstyle=\tfe
]
\starttext
\startchapter[title={With a rule}]
Bla bla bla
\stopchapter
\stoptext

Answer 1

It is not perfectly clear to me how you want it to look, but you can try this (see some comments in the code):

\definehspace[oneem][-.125 em]
\starttexdefinition MyNumberChapterCommand #1
    \tfe #1
    % {\tfe #1}% Test this instead of the one above
    % #1% Test this if the numberstyle is enabled
    \hspace[oneem]
    \blackrule[
        height=\strutheight,% I changed \lineheight to \strutheight
        depth=\strutdepth,
        width=2pt,
        color=darkred,
    ]
\stoptexdefinition
% \definebodyfont[12pt][rm][tfe=Serif at 36pt]
\definefontsize[e]
\definebodyfontenvironment[default][e=3]% 3*12=36
\setuphead[chapter][
    numbercommand=\MyNumberChapterCommand,
    page=no,%Just to have them on the same page here

    % numberstyle={\definedfont[Serif*default at 36pt]},
]
\starttext
\startchapter[title={With a rule}]
Bla bla bla
\stopchapter
\stoptext

The version of the code shown above gives (I think the number and the rule look too cramped):