Compound shapes is in Affinity Designer is found in the layer menu in create command. Select two or more curves / paths in the application and you will be able to apply it.
Go to the layers pane and you will see an entry for it and inside that, you will your two paths. The top entry will be above the bottom entry (on the art board and in the panel) and the top entry will have a little icon beside it with a check box ON and the icon can be clicked (as can the check box) and a menu will appear listing add / subtract / intersect / XOR
Change menu from first item to the second so instead of combining the top and bottom entry, you will now see the top item item chopped away from the bottom item, though only if there is some overlap. Change it to the third item and if there is some overlap with the two vector designs then only that overlap will remain. Select the fourth item in the menu and where there is an overlap, that will be removed and only the non overlapping parts will remain.
You can select the top item (or bottom item) by going to the layers panel, if you try on the art board you will just select the combination. Once you have the top item selected then you can resize it or rotate it as well as move it and as you do so the live effect will be updated and you will see the result of the overlap change. If you move the path totally away from the path there is no overlap and 2nd will just display the bottom path with the top path vanishing and the 3rd item will result in no paths at all. You can move either item around and you will see the end result depending on the overlap.
Note that the color used in this combination of paths is fixed as initial first color, however, once it has been set, it appears not be changeable and selecting either item and trying to change the color appears to make no difference. So if the first path is red then it will be red throughout until expanded via the convert.
You can select both of the paths and then go to the layer menu and use the release command and you will just end up with your two paths with no overlap etc.
Select both of the paths and then use the convert to curves command and you will just have the end result of the combination and it will no longer be live. You can re-start to create another one via the layer menu.
You can do the same with more than two paths and when you select four paths, you will notice that the top three items in the layers panel will have the icon (and a check box) beside them and you can change the menu for each and individually so one can be the 2nd menu item and the other can be the 3rd etc. It can get quite complex and messy and often a little baffling to what combinations work or not but you can still select the layers and move them around and the overlaps will change based on the above logic. Again, once you are happy with your various combinations of paths, you can convert them all to curves and then manipulate them using other tools such as the node tool etc.
Select the container for the paths and then go to the fx and set a 3D, shadow etc. You can't select one of the items inside the container and change those, that is just ignored.
You can also convert this design into a symbol via the first button in the symbols panel at the top, click that and the item will be added there and you can then make multiple instances of the artwork and all will contain the compound and all will still be live. Edit one of the entries and all the instances will change.
You can create multiple levels of these designs. Select a vector and another vector. Use the command and you now have them joined and you can add / subtract / etc. You can also go to the container of those two vectors and hold down the alt or option key and duplicate the container and both of those containers can now be selected and you can then goto the same command as before and there will be a container for both of those sets. One of the item (the one that was duplicated) will have the add / subtract feature and the original will not so you are adding and subtracting from the original with the duplicate. You can select that overall container and hold down the alt / opt and duplicate that and then go to the command and then use that as a container and so on. It is all still live. You can also change any of the add / subtract etc to another setting in any of the vectors included as well as for the containers. You can also duplicate the container and drag the container into the artwork and use that as clipping for the artwork and that is also still live. You can then also drag that super container / clipped artwork into the symbols panel and make it a symbol and then move the item inside another container (using the arrange menu and move inside) and then duplicate that symbol (which is made up of all the masks / add / subtract etc) and then any changes to the add / subtract etc will be reflected all the way up to the super super container and so on. You can see all the levels in the layers panel. You can also, if you wish, edit this in Photo via the edit in Photo command and use it with features there such as patterns etc. At any point, you can use the convert to curves to expand the entire design so you can edit the nodes etc