Click on the line symbol in the table of contents to open the Symbology pane.
In the Gallery search for Arrow.
Choose one of the options (I'll choose Arrow at End) and then switch to the Properties.
Shape marker should be highlighted > click on Font > find the ESRI Arrowhead font.
Choose a style of arrowhead and adjust its properties.
For whatever reason I can't see any arrows after doing this. The same thing happened in ArcMap, and to remedy this, I increased the "Number of Positions" to around 100 in Line Decoration Editor screen, and this showed me arrows at regular intervals across the line pointing in the direction of the next point based on the date attribute. I can't seem to find the "Number of Positions" feature in ArcGis Pro. Perhaps there's another way to do it?
Try this. From the line symbol Properties Structure dialog (the little wrench), under Layers > choose Add symbol layer.
Add Marker Layer.
Switch back to the Properties > Layers dialog part of the pane and you'll see that in addition to the standard solid stroke part of the line, you now have a shape marker layer.
You can follow the step from the previous post to click Font > search ESRI Arrowhead and choose a symbol you want.
Under Marker Placement the placement can be set to Along line and control the frequency with the Placement template.
Here is a placement template of 50:
Here is what it defaulted to at first with a placement template of 16:
This seems incomplete? As it doesn't seem to actually read the digitization direction or a one way code to tell you which? or at least if you select start and end, then the arrows are just pointing to the adjacent line segment?