I understand you're looking for the Pantone TCX color book in PDF format. However, I should let you know that Pantone color guides (including TCX, TPX, or any official swatch books) are copyrighted commercial products — they are not legally available for free download as complete PDFs.
While not "official" books, several industry suppliers and document-sharing sites host PDF references for TCX colors: Can I try Pantone Connect Premium for free? Pantone Tcx Color Book Free Download Pdf
To understand the value of the TCX book, you must first distinguish it from its cousin, the TPX. I understand you're looking for the Pantone TCX
If you are working professionally in textiles, a physical reference is often necessary. Pantone Cotton Swatch Card What Exactly is the Pantone TCX System
(Hypothetical title—real papers exist on color standards)
What to search: Pantone TCX color communication textile design
Why interesting: Discusses how TCX (cotton swatch format) differs from TPX (paper) and why digital representations fail without physical standards. Looks at supply chain mismatches between designers and manufacturers.
in Adobe Creative Cloud to browse colors for free, though a premium subscription is required to use them directly in design files. Unofficial PDF Reference Charts