In the desktop versions you can hover your mouse cursor over an enemy and get a text description of their health ("Injured", "Nearly Dead", and the like).
I'm not sure how one would do this in the tablet/touch versions.
If you hold Tab while hovering the cursor over an enemy's head, you can see a general description of how wounded they are: "Uninjured", "Barely Injured", "Injured", "Badly Injured", or "Near Death".
although that's a pretty cool idea, I don't think it'll get implemented.. you can easily check out mob health, as well as other useful info such as ability scores/inventory/innate & memorized spells/abilities in Shadowkeeper.
Knowing the exact hit points of an enemy might have been useful for BG2 and ToB, for using Power Word spells. (they oparate based on target's current hitpoints) Now you need to estimate from its description 'Badly Wounded'. But a 'Badly Wounded' huge dragon with tons of HP originaly might still be out of the HP range of PW:Kill for all you know.
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I'm not sure how one would do this in the tablet/touch versions.