The primary way to get Pantone colors back into Illustrator is through the official plugin:
/Applications/Adobe Illustrator [Your Version]/Presets/en_US/Swatches download pantone colors for illustrator link
You downloaded the file, installed it, but Illustrator crashes or the colors look grey? Here is why: The primary way to get Pantone colors back
This is the only official way to access over 15,000 up-to-date Pantone colors directly within Illustrator. download pantone colors for illustrator link
If you have an older version of Illustrator or a backup, you can manually copy the legacy .acb (Adobe Color Book) files into your new installation. Pantone Connect | Adobe Exchange
Before Illustrator 2022 (v26+), Pantone books were built-in. If you have an older version: