How to setup the interlinespacing parameters as function of x-height

Questions
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2

Welcome to the forum @Garulfo ,

This is a classic case of Why is the value I receive from context always content? .

Solution will require you to move the context expression outside of the x-height definition. Hint: turn it into a function and provide context to it.

// Requires `context`
#let x-height(body) = {
  {
    measure(
      box(
        inset: 0pt,
        outset: 0pt,
        text(top-edge: "bounds", body),
      ),
    )
  }.height
}

#let body = [= Test
  #lorem(20)]
#body

#context {
  let height = x-height(body)

  set text(
    top-edge: 2.8 * height * 0.72,
    bottom-edge: 2.8 * height * 0.28,
  )
  set par(leading: 2.8 * height * 0.28)

  body
}

If you could please edit your first code snippet and enclose it in back ticks ``` snippet ```, that would help us copy/paste/read your code more easily. Thanks.