Photoshop CC 2019 was a mature product within Adobe’s Creative Cloud (CC) subscription ecosystem. This model represented a complete departure from the old Creative Suite (CS) days, where users paid a large, one-time fee for a perpetual license.
If you are looking for a "free trial" of Adobe Photoshop CC 2019 today, you likely won't find it directly from Adobe. Currently, the official Adobe free trial only provides access to the of Photoshop.