Apply the Tint effect and use the eyedropper to sample your value (or two, using both boxes). From there, you have a couple of options:
1 - copy the Tint effect and paste it elsewhere, disable the FX button while keeping the color rectangles revealed, and use the color box to do another eyedropper sample
2 - after eyedropping the color, click the color rectangle box and copy the Hex value (#), and paste that into your destination color value
If I have a color palette to use throughout a sequence, I’ll make a PNG of it in Ae, import into Pr, and load that into the Source monitor placed next to the Effect Controls for eyedropping.
Sort of off-topic: In Ae I can see the RGB values in t6he info box by simply by moving the pointing device over the footage. Is there anything like that in Premiere? Or do I have to use Resolve or Avid to get this kind of feedback?