Since folks have mentioned Q rings I thought I’d mention this Garmin Connect IQ data field
It can only be used if your power meter supports “torque efficiency” and “pedal smoothness”.
If it does then it gives a handy number that indicates how many watts you may be wasting while pedaling.
I’ve found it to be a handy reference especially during longer rides. As I fatigue this number drifts up. For me simply feeling my foot engage a little earlier at the top of the stroke reduces this number and the actual watts go up for next to no feeling of extra effort.
Another use is just trying to make the numbers change from low to high and back to low and seeing if there is any link to how it feels in terms of effort and resultant power,
DIfferent folks may find different things work for them, Whatever there really isn’t any downside to giving it a try so I’d suggest checking it out if you have a Garmin
(it seems to work fine despite saying its in beta)