简单一点就是在最后的可选参数里加一下:
\titleformat{\chapter}[block]
{\normalfont\ChapterFont\color{myblueii}}
{\tcbset{colframe=mybluei, boxrule=0.8pt, left=0pt, right=0pt, top=0pt, bottom=0pt}\hskip 0.25em\mbox{\tcbox[ boxsep=12pt, colback=mybluei, tcbox raise = -10pt]{\color{white}\bfseries\fontsize{65}{65}\selectfont\thechapter}}}
{0.5 em}
{#1\vskip0.6ex\endgraf\titlerule[1ex]}[\vskip-3em]




问 正文与定制标题之间的间隔怎么缩小?