Font settings include a weight dropdown, which gives precise control over how heavy the text appears.
Setting the weight
Select the text element, open font settings, then choose a weight from the dropdown. Available weights depend on the font selected, and commonly include light, regular, medium, and bold.
The dropdown is keyboard accessible, and closes when focus moves elsewhere or Escape is pressed.
Why the options vary
Weight availability is a property of the font itself. A font published with only one weight offers only that weight, while a family with a full range offers all of them.