Oh ... as to within Lumetri, shot-matching. Right.
Build a new workspace with a 'new' panel that has both the Reference monitor and Program monitor in it, preferably put on your second and properly calibrated 'good color' monitor. Save it as say ShotMatching, then use the workspace bar managing box to move it onto your workspace bar for quick selection.
Use the mini-timeline within the Reference monitor to move to the clip you want to match.
Use the main timeline to set the Program monitor to the clip you want to correct to match the one showing in the Reference monitor. Adjust magnification as desired. If say balancing for skin tones, magnify each so that you're mostly seeing only skin-tones.
You may need to note where in the timeline the Reference monitor frame you're using is, so you can move the main timeline to that to get a view of the scopes for that clip, then set it back to where the clip is you're working now, and see the difference in the scopes. It would be WONDERFUL if one could simply click in the Reference Monitor & have the scopes go to that, click in the Program monitor & the scopes go to that clip ... but ah well. That would be easier, wouldn't it?
IF YOU HAVE OVER-BRIGHTS IN YOUR CLIP ... ! Meaning signal up above the 99 mark in the RGB Parade scope left-side graticules ... drop an RGB Curves effect on the clip, go to the Effects Control panel to grab & slide that up ABOVE (therefore before) the Lumetri effect in the Effects Control Panel, then use the Master or individual channels to either simply bring the 'lost' highlights back down or even do a basic neutralization of the clip. ANY SIGNAL ABOVE 99 GETS LEFT UP THERE by most of the tools in the basic tab. NOT good to view.
NOW ... you're ready to start matching. And for this work, I HOPE you've got an external control surface ... as it makes this SO much faster and gives better results. Say, the Ripple, for $350USD or thereabouts. Will save you more than the cost in a very few projects.
Neil