How to Set Text Format by User-Defined Function with Input as String

Question

I have simple but annoying problem here. I guess it occurs to many Mathematica users.

The thing is that I wish to define a function to format the text in Mathematica. Yet, I don't know whether it is possible.

Say if I want to make a plot with FrameLabel set, like the following script:

Show[
 Plot[x^2, {x, 0, 1}, PlotRange -> {{0, 1}, {0, 1}}], Frame -> True, AspectRatio -> 0.8,
 FrameLabel -> {Style[ToExpression["x", TeXForm, HoldForm], 18,FontFamily -> Times, Bold], 
 Style[ToExpression["x^2", TeXForm, HoldForm], 18, FontFamily -> Times, Bold]},
 RotateLabel -> False
 ]

which generate this plot

The thing is I have type this bothering format setting script again and again if I need to plot a lot, though the format I set every time is the very same.

Style[ToExpression["x^2", TeXForm, HoldForm], 18, FontFamily -> Times, Bold]}

Therefore, I am wondering if I can define a function to overpass such prolix script. For example,

SetStyle[input_] := Style[ToExpression[ToString[input, InputForm], TeXForm, HoldForm],18,FontFamily -> Times];

It works for superscript, but it fail in the most of the Latex input, like \\theta or \\frac{x}{2} and even just the subscript like x_0

anyone know how I can fix my code?

Thanks for your kind and generous suggestion.

Answer 1

First, I would like to give this credit to Alexei Boulbitch. He made a little but critical amend in the input argument of my original code.

The function should be defined as following , instead,

st[txt_String] := Style[ToExpression[txt, TeXForm, HoldForm], 18, FontFamily -> Times, Bold]

In this way, the input of the function could be a string and the problem mentioned above could be perfectly solved!

For example, one can set the FrameLabel like given by Alexei

FrameLabel -> {st["x"], st["x^2"]}

It works even for a complicate LaTeX input, for example,

FrameLabel -> {st["\\frac{x}{C}"], st["\\phi_0+\\theta_1"]}

Once again, thank you @AlexeiBoulbitch