代码：

from docx import Document
from docx.shared import RGBColor
obj= Document('装机必读调整样式.docx')
word ='软件'
def set_run(run):
   #设置run的字体大小、是否加粗以及字体颜色
   run.font.size = font_size
   run.bold = bold
   run.font.color.rgb= color
for p in obj.paragraphs:
   for r in p.runs:
       if word not in r.text:
           pass
       #获取当前run的字体属性
       font_size =r.font.size
       bold =r.bold
       color =r.font.color.rgb
       #使用关键词切分当前run的文本
       rest =r.text.split(word)
       #清除当前run的内容
       r.text = ''
       for text in rest[:-1]:
           run = p.add_run(text=text)
           set_run(run)
           run = p.add_run(word)
           run.font.size = font_size
           run.bold = bold
           run.font.color.rgb=RGBColor(255,0,0)
       run = p.add_run(rest[-1])
       set_run(run)
   obj.save('装机必读调整之后样式.docx')

执行结果：