KOMA：章节和标题样式（大写 + Chapterprexif）

Question 1

您已设置选项chapterprefix=true，因此必须重新定义\chapterlineswithprefixformat：

\renewcommand*\chapterlineswithprefixformat[3]{%
  \ifstr{#1}{chapter}
    {#2\MakeUppercase{#3}}% changed definition for chapter
    {#2#3}% original definition for other levels with style=chapter
}

为了使章节标题右对齐，请重新定义\raggedchapter为\raggedleft：

\renewcommand*\raggedchapter{\raggedleft}% <- chapter alignment

\chaptermarkformat可以简单地重新定义以删除章节名称：

\renewcommand*\chaptermarkformat{\thechapter\autodot\enskip}% for header

请注意，有一个选项markcase=upper可以将左标记和右标记设置为大写：

\usepackage[
  automark,
  markcase=upper% <- uppercase for left and right marks
]{scrlayer-scrpage}
\ohead{\headmark}% <- changed

例子：

\documentclass[
  paper = a4,
  twoside = false,
  numbers = noenddot,  
  parskip = half,
  listof = flat,
  listof = entryprefix,
  chapterprefix = true,
  listof = nochaptergap
]{scrreprt}
\usepackage[T1]{fontenc}% <- added

\RedeclareSectionCommand[
  innerskip=0pt,% skip between chapter prefix and chapter title
  prefixfont=\LARGE% font of chapter prefix
]{chapter}
\renewcommand*\raggedchapter{\raggedleft}% <- chapter alignment
\renewcommand*\chapterlineswithprefixformat[3]{%
  \ifstr{#1}{chapter}
    {#2\MakeUppercase{#3}}% changed definition for chapter
    {#2#3}% original definition for other levels with style=chapter
}
\renewcommand*\chaptermarkformat{\thechapter\autodot\enskip}% for header

\renewcommand*{\sectionformat}{%
  \makebox[1.15cm][l]{\thesection\autodot}%
}
\renewcommand*{\subsectionformat}{%
  \makebox[1.15cm][l]{\thesubsection\autodot}%
}  

% ============================================
% HEADER & FOOTER
% ============================================
\usepackage[
  automark,
  markcase=upper% <- uppercase for left and right marks
]{scrlayer-scrpage}
\clearpairofpagestyles
\ohead{\headmark}% <- changed
\ofoot*{\pagemark}
\setkomafont{pagehead}{\sffamily\bfseries\upshape}
\addtokomafont{pagenumber}{\sffamily\bfseries}

\begin{document}
\chapter{Introduction}
\section{Section}
\newpage
Lorem ipsum
\end{document}

结果：

或者使用\textls*包提供的包microtype：

代码：

\documentclass[
  paper = a4,
  twoside = false,
  numbers = noenddot,  
  parskip = half,
  listof = flat,
  listof = entryprefix,
  chapterprefix = true,
  listof = nochaptergap
]{scrreprt}
\usepackage[T1]{fontenc}% <- added
\usepackage{microtype}% <- added

\RedeclareSectionCommand[
  innerskip=0pt,% skip between chapter prefix and chapter title
  prefixfont=\LARGE% font of chapter prefix
]{chapter}
\renewcommand*\raggedchapter{\raggedleft}% <- chapter alignment
\renewcommand*\chapterlineswithprefixformat[3]{%
  \ifstr{#1}{chapter}
    {#2\textls*[75]{\MakeUppercase{#3}}}% changed definition for chapter
    {#2#3}% original definition
}
\renewcommand*\chaptermarkformat{\thechapter\autodot\enskip}% for header

\renewcommand*{\sectionformat}{%
  \makebox[1.15cm][l]{\thesection\autodot}%
}
\renewcommand*{\subsectionformat}{%
  \makebox[1.15cm][l]{\thesubsection\autodot}%
}  

% ============================================
% HEADER & FOOTER
% ============================================
\usepackage[
  automark,
  markcase=upper% <- uppercase for left and right marks
]{scrlayer-scrpage}
\clearpairofpagestyles
\ohead{\headmark}% <- changed
\ofoot*{\pagemark}
\setkomafont{pagehead}{\sffamily\bfseries\upshape\textls*[75]}% \textls must be the last command
\addtokomafont{pagenumber}{\sffamily\bfseries}

\begin{document}
\chapter{Introduction}
\section{Section}
\newpage
Lorem ipsum
\end{document}

但请注意 KOMA-Script 文档中的这句话：

除此之外，印刷师一致认为，只要您将整个单词或短语设置为大写字母，就绝对需要额外的间距。但是，在所有字母之间添加固定间距并不是一个充分的解决方案。不同的字母对之间需要不同的间距。此外，一些字母已经在文本中产生了必须考虑的间隙。像 ulem 或 soul 这样的包几乎无法实现这一点，\MakeUppercase 也不能。使用 microtype 包的自动字母间距在这方面只是一个近似的解决方案，因为它没有考虑到具体的、依赖于字体的字形。因为排版全大写文本是专家工作，几乎总是需要手动调整，所以建议普通用户避免使用它，或者只谨慎使用它，不要在运行头等暴露的地方使用它

Answer