You can create a continuous transition, or tempo curve, between two tempi using a tempo curve.
Select the two tempo points.
Click-hold and drag the tip of the right angle line (the corner) above or below the second tempo point.
A curve or diagonal line results (a Move Curve Node help tag is shown), which can be dragged—horizontally or vertically—to alter the curve shape. The process is similar to drawing track automation curves with the pointer.
Choose a value from the Snap pop-up menu in the Tempo track to define the number of tempo changes that are actually performed when using curves.
When set to 1/16, there are four tempo changes per quarter note; 1/1 only generates one tempo change per bar, which resultsu in a more abrupt transition. A different snap value can be defined for each tempo curve.
Click the curve node (at the tip of the right angle) with the Eraser tool, or double-click it with the Pointer tool.