First of all, I want to emphasize that the new HEIF image format is way more powerful than the legacy JPEG, so you should avoid conversion for as long as possible. HEIF offers both, a superior image quality, and a smaller file size. JPEG was created in 1992 and HEIF was finalized in the summer of 2015. Those 23 years make a significant difference. The first major company to support the new format is Apple with its latest devices and Mac operating system. Neither Android nor Windows support it. You'll find real examples of how JPEG/HEIF compare here. High Efficiency Image File Format Taking the above into account, I assume you're having problems opening HEIF on your Windows PC. Check this system utility that adds support for .heic photos to Windows. CopyTrans HEIC It also offers right-click menu conversion to jpg if really needed.
So if you want a quality image with just over 2/3 the size, this tool will help.