Is it possible to create an action for finding black and white points?

@BGering – I have never had good results, although YMMV:

Image > Adjustments > Match Color

The lighting is a much bigger variable than endpoints. If shot in different lighting, matching the endpoints won't make them look anywhere near similar.

Which is why I fully agree with Stephen. This can only be done by eye, by a human.

Trevor suggested a traditional, tried and tested way of finding an image’s black and white points. If you need more details about how to think through this feature, you can refer to the following article by the great Bruce Fraser written 23 years ago but still works just as well, as Trevor showed.

https://creativepro.com/out-of-gamut-don-t-underestimate-photoshop-s-auto-color/

If I was doing this, I think the way I’d set up an action is:

1. Set the Auto Color Correction Options defaults as instructed, adjusting the Clip percentages with a test batch until you think it gives you the result you want across the kinds of images you’re feeding it. 

2. Click Save As Defaults. Not only does this set the defaults in the Auto Color Correction Options dialog box, I think it also sets the defaults for when you choose Image > Auto Tone. 

3. Because of #2, I think that when building the action, you just have to choose Insert Menu Item in the Actions panel menu and have it insert Image > Auto Tone. That should apply the defaults you worked out. 

If you find it difficult to work out a single set of Clip percentages that works well for all the images you need to process, you might look into batch processing with the Auto feature of Adobe Camera Raw or Lightroom instead. That’s a more recent AI-trained method that should be better, but it depends on your images. If that doesn’t work either, you may have to consider a more manual way of setting those clip points.

I do not recommend using auto colour corrections if you want the best starting point. Set the white and black points manually using a significant area of visual importance in each image. This is a critical human-based assessment beyond simple auto-algorithms that have no idea of the nature of the actual image content.

I've not tried this, but I think you should be able to save a profile in Curves or Levels and use that in the action.  It would be easier to use one of the Auto presets.

• Open a Levels Adjustment layer, and Opt click Auto, which will open up the options panel.
• The default is Enhance Brightness and Contrast, but experts like Jesus Rameriz (The Photoshop Training Channel) say to use Find Dark and Light Colors.
• Click to select Find Dark and Light Colors and set how hard you want to click light and dark tones.  The default is fine.
• click on OK twice.
• Test to see if running levels goes with this new setting.
• Add Flattern layers to the end of the action

IO have just had visitors arrive so I have to dash, so try, and if it doesn't work, w can ask one of the Scripting experts to see if they can set something up.

BTW if you add Save to an action, it will always use the folder you used when creating the Action.  What I do is consider that folder as a temporary location, and move them when done.  If it works, then you can use Image Processor to batch the entire folder of files and check to run your Action inside Image Processor.

Good luck.