At the extremes low pour over extraction would be tangy, green, tree bark sort of flavours. Slightly higher extraction may be less tangy, but more charred/iron/lacking sweetness. Ideal would be clean, most transparent, the notes most accessible. A little over might start to edge a little drier (but still may be fine until the last sips). Overextracted is the least common fault but would be a hoppy/smokey dryness specifically (not bitterness in general).
These are all dealt with by grind adjustments, at a single grind setting & brew size, you will not experience more than a couple of these and certainly not the full span from under to over.
Beyond extraction (which is only concerned with dissolved solids, it doesn’t consider outside malfunctions) you can still screw up a brew with the non dissolved solids. So once you are broadly dialled in, if everything tends to be dry/powdery/charred, especially in the first sips, or there are no flavours coming through because it all tastes charred/charcoal try going coarser or limiting agitation,
If everything has a sour edge, but is otherwise clean, try going a little finer and see if you can lose it, without generating too much silt/ non dissolved solids in the cup.
Mainly, you are looking for common & similar malfunctions (at the same grind setting) that present the same, even when your coffees have very different notes.
Don’t make adjustments based on a single coffee, sanity check against another bag to rule out a badly/over roasted bag throwing you off course.
In my experience the 2 main problems are, in this order:
Coffee roasted too dark.
Grinding too fine/too much agitation ruining cups that are extracted well but too silty.