The content of the Definitive Edition (improved lighting, Lara’s updated model, particle effects, and all DLC) was rolled into the base PC version via a free update shortly after the PS4/Xbox One release. On Steam and other PC stores, the full package is simply called Tomb Raider or Tomb Raider GOTY Edition (which includes all DLC).
It looks like you’re looking for the for Tomb Raider (2013) Definitive Edition on PC. Tomb Raider 2013 Definitive Edition Pc
However, there’s an important technical clarification to make first: The content of the Definitive Edition (improved lighting,
That said, below is for the PC version as it exists today (effectively the Definitive Edition content). Promotional Text for Tomb Raider (2013) – PC (Definitive Content) Title: Tomb Raider (2013) – PC Definitive Experience Lara’s updated model