代回答一下
打開ssa字幕(用筆記本打開即可)
[V4 Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, TertiaryColour, BackColour, Bold, Italic, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, AlphaLevel, Encoding
Style: Default,華康中圓體,18,&Hffffff,&H00ffff,&H000000,&H000000,-1,0,1,2,3,2,20,20,30,0,1

把18改成你想要的大小即可