Professional HEIC to PDF converter software usually offers greater flexibility and advanced features. These software are usually designed to be very user-friendly and support fast batch processing and more complex file processing tasks, such as image quality control, page layout settings, etc.
Here are some recommended options:
TunesBro HEIC Converter:
TunesBro HEIC Converter is a free tool specifically designed to convert HEIC files to JPG , PNG and PDF formats, This program is simple to use and is suitable for users who only need basic conversion functions.
You can Google TunesBro heic converter to see their official site.

Adobe Acrobat Pro:
Adobe Acrobat Pro is an industry-leading PDF tool that provides comprehensive PDF creation, editing, conversion and management functions. It supports converting HEIC to PDF and provides a wide range of editing tools such as page reflow, annotation, encryption, etc. Although it is a paid software, it is comprehensive and especially suitable for professional users.
The benefit of using these third-party software is that they usually provide more customization options and more powerful functions to meet various complex needs.