I don’t think it’s possible to achieve this just by styling. You could use Right Indent for every second line, but that would require you to make manual line breaks which would be a mess.
I will suggest something different. Why not use Text Wrap for this? Simply make the paragraph justified and use invisible rectangles which prohibits every second line from having the full length.
Place a rectangle with the wanted width on every odd line and apply Text Wrap set to Wrap around bounding box with no Offset.
Make the rectangles transparent and place them on the Master Page (or simply copy/paste them onto each page where you need the styling).