You can extend functionality and make adjustments for .css / .xml / .phtml / .js  files in Magento 2. The workflow and adjustments below are applicable to any Magento 2 extension

Summary:

  • Using a child theme for Magento 2 customizations.
  • Magento 2 .css customization.
  • Magento 2 .xml customization.
  • Magento 2 .phtml customization.
  • Magento 2 .js customization
  • Add custom code in Footer and Head via Magento admin options
  • Specific Pearl Theme CSS/JS options for individual Category Pages, Static Pages and Static Blocks.
  • Additional Magento Customization not explained in the examples above

 

Source: How to customize css / xml / phtml / js files in Magento 2 – examples [ Tutorial ] – WeltPixel Support Center