Hello  @Tom Liu,
In order to increase the height line height you would need to add custom CSS.
Please follow the steps below:
1. Log in to your admin area
2. Go to “Appearance >> Customize >> Additional CSS”
3. Add the below mentioned CSS rule:
   p, li{
   line-height:25px;
   }
You could change the height by updating the pixels from 25 to whatever suits your needs.
This should get you the results you wanted.
Thank you
Regards,
Team ProDesigns Themes