\documentclass[a4paper]{book}
\usepackage[most]{tcolorbox}
\usepackage{amsmath}
\usepackage{ptext}
\usepackage{xepersian}
\settextfont[Scale=1]{Yas}

\newcounter{mycounter}
\numberwithin{mycounter}{chapter}
\renewcommand{\theequation}{\themycounter}

\newcommand\theoname{قضیه}
\makeatletter
\newtcolorbox{theorem}[2][]{
breakable,
enhanced,
colback=orange!07,
colframe=orange!07,
top=25pt, %\baselineskip
enlarge top by=\topsep,
overlay unbroken and first={
  \node[xshift=-10pt,yshift=-15pt,rounded corners,anchor=east] at (frame.north east) % thick,draw=blue,fill=blue!20,
  {\setRTL\hboxR{\refstepcounter{mycounter}\strut{\color{red}{\themycounter~~\bfseries{\theoname}}}  \label{#2} \if#1\@empty\relax\relax\else~(#1)\fi}};
  }
}
\makeatother
\begin{document}
\chapter{عنوان فصل}
\begin{theorem}{t1}
\ptext[1]
\end{theorem}
\begin{theorem}{l2}
\ptext[4]
\end{theorem}
\begin{align} 
a & = b+c  \\
d & = 1 
\end{align}
\end{document}