To be clear, this technique will get you close, but not as close as Photoshop will. I'll show an example at the end for comparisons sake.
Now, to do this, there are actually a couple of different approaches, but I liked this one the best, so step by step:
Step 1: Import Image
Under the Actions (wrench) menu, select "Add" and then "Insert Photo":
Select the photo you want (I fit mine to canvas, up to you) and import. At this point, I named the layer Photo for reference purposes. You can also import a photo into a new project through the Gallery menu.
Step 2: Duplicate "Photo" layer
So, now duplicate this layer and name it Inverted.
Step 3: Invert the "Inverted" layer using Curves
Under the Adjustments (magic wand) icon, select Curves and then reverse the slope of the curve.
You can play with these values to tweak the end result or work with specific colours impact the behaviour of the next steps.
Step 4: Duplicate the Inverted layer
Duplicate Inverted and name it Grayscale
Step 5: Desaturate the Grayscale layer
Under Adjustments, select "Hue, Saturation, Brightness" and slide the "Saturation" scale all the way to the left.
Step 6: Duplicate the Grayscale layer
Duplicate Grayscale and label it Lineart. We're almost there!
Step 7: Change the blend mode
In the Layers menu, select the 'N' and in the menu, select "Difference" and then "Divide" (this will make the layer entirely white).
Step 8: Blur to reveal
With the Lineart layer selected, go to Adjustments and select Gaussian Blur. Slide until you're satisfied with the result.
For comparison sake, here's the output from Photoshop using find edges filter:
Clearly Photoshop produces a sharper outcome, but as you experiment with this workflow in Procreate, you'll find some settings that work best for your purpose.
Clearly Photoshop produces a sharper outcome, but as you experiment with this workflow in Procreate, you'll find some settings that work best for your purpose.