On some commands (Offset, Fillet, Chamfer, Trim/Extend) an additional input option 'Distance' is available as shown here . If displayed then Draft it only requires a distance to be input and an updating dynamic dimension is displayed, moving with the cursor. Click to accept the current value.
Alternatively you can type in the value. Click in the input field and you can edit the value as required (double click in the field to select the whole current value which can then be deleted or over typed). As soon as you type in the field Draft it will lock the field and the dynamic dimension will be locked. You must click the button to unlock if you wish release the value. To accept the value click the mouse when the cursor is within the drawing area. The value is unlocked automatically as soon as the point is accepted.
It is possible to switch between the 'Distance' and Snap input options as required (Shortcut keys & respectively). Draft it remembers the last used setting.