This is just to get you started: The format of true/false has been adjusted, especially that it also repeats the question. For an answer you need to add the respective "True" or "False" in an environment on its own (I do not think you can avoid it easily given how xsim handles solutions, so I cannot even prepare a thin wrapper for you).
What I did not include at this point is the exact answer formatting. First of all, you would need to retrieve the solution body and then you would have to make comparisons to check whether true or false should be bold. The current implementation just outputs the correct answer.
Please note that setting the appropriate keys (truefalse
, booleansolution
) with their show/hide options will work independently from the normal exercise/solution pair.

% arara: pdflatex: {shell: 1}
\documentclass[10pt,a4paper]{article}
\usepackage[verbose,clear-aux]{xsim}
\usepackage{amssymb}
\DeclareExerciseEnvironmentTemplate{tf}
{%
\UseExerciseTemplate{begin}{default}%
\IfInsideSolutionT{\GetExerciseBody{exercise}\bfseries}%
}
{%
\IfInsideSolutionF{(True/False).}%
\UseExerciseTemplate{end}{default}%
}
\DeclareExerciseType{tf}{
exercise-env = truefalse ,
solution-env = booleansolution ,
exercise-name = Question ,
solution-name = Solution ,
exercise-template = tf ,
solution-template = tf ,
counter = exercise
}
\xsimsetup{
truefalse/print = true,
booleansolution/print = true,
path=./exercises,
file-extension = tex,
exercise/template = bonus,
grading-table/template = default*
}
\begin{document}
\begin{truefalse}
The earth is the fourth planet from the sun.
\end{truefalse}
\begin{booleansolution}
True.
\end{booleansolution}
\end{document}