Refer to the series of screenshots below:
Step 1 Place a section of path with sidewalks
Step 2 Continue with another section without sidewalks as wide as you want the crossroad to be.
Step 3 Continue with another section with sidewalks
Step 4 Create a separate section of path with sidewalks and after rotating it, place it on one side of the section without sidewalks (I prefer to disable snap to grid her to get a more precise plcement so that the node with the arrows are in the center of the no-sidewalk section and just touching it)
Step 5 Using the Path properties road size, adjust the width until the sidewalks look ok.
Steps 6 & 7 Just repeat Steps 4 & 5 on the opposite side
And here is your crossroad with sidewalks.