Photoshop UI displays very small compared to all other Adobe software UI

Photoshop responds to the scale factor setup in your operating system preferences. The larger the scale factor in your system preferences, the larger Photoshop scales the user interface. This allows the user to adjust the size of the user interface and provide crisp text.

Photoshop adjusts its resolution based on your macOS Displays System Preferences:

In macOS, select System Preferences > Displays. Now, under Display, choose either Default for display or Scaled to select a resolution setting. See Apple Support for Change your Mac display’s resolution.

https://helpx.adobe.com/photoshop/kb/hidpi-retina.html

IF after that, you see just the PS GUI too small, reset your preferences. Better? 

Press and hold Option+Command+Shift (Mac OS) immediately after launching Photoshop.

2560 x 1440 The default resolution. I Just got this 27" studio display (5k). Previously I was using the Apple Thunderbolt display (2011) and everything looked normal with all the UI's

That's a 'calibration' preset. I'm referring to the actual display resolution by the pixel value. Resoution>Scalled setting. 

See: https://helpx.adobe.com/photoshop/kb/hidpi-retina.html

Im using the Design & Print (P3-D50) preset. Resolution is Default for Display. I've toggled between a few but same results

What display resolution are you running and have you altered it otherwise?