Its the "inertia" study in ThinkorSwim."LRMA on the upper, then below is price vs the LRMA with two more LRMA"
Measuring trend strength would be a necessary 1st step in producing what OP is looking for.
For the 2nd step "predict what a reasonable pullback zone can be based on the strength",
is your LRMA study designed to predict the depth or duration of a
Reasonable Pullback Zone Valley
for the Correction Wave
based on the Trend Strength?
View attachment 265801
Basically, its measuring price changes relative to estimates of a linear relationship between time and price. You have to remember, though, its not a point estimate, and the distribution of error terms is unknown. So you can't really use it to "normalize" trend or momentum.
Its like calculus. An LRMA is essentially a way to differentiate price.
This study is 'differentiating' a differential of price and a linear estimate of trend.
https://tlc.thinkorswim.com/center/reference/thinkScript/Functions/Statistical/Inertia
You could say its measuring momentum, or deviation from trend, or trend strength.