A labelled leader: an arrow on the drawing, a box you type into at the other end.
A Callout is a Text Box with a leader on it. The arrow lands
on the thing being described and the label sits clear of the drawing.
Draw it: press on the thing being called out, drag to where the label should sit, release, then
type.
Settings
Line Weight: 1 to 10, default 1. Sets the leader only.
Colour: the leader and the box border.
Fill: the label box background.
Font size: default 18. Independent of Line Weight, so thinning the leader does not shrink the text.
Font colour: its own channel.
Corner radius, Padding: as the Text Box.
Notes
The arrowhead is at the end you pressed, not the end you released: start at the target and drag away from it. That is the opposite of Arrow, where the head lands where you finish.
The head is a solid arrow, the drafting-standard leader head. An open one reads as a stray chevron at plan scale.
The label is born upright however the page is rotated.