Is there a way to bring back the add menu that pops up in the bottom in Blender 2.8 when adding primitive object to your scene to change vertices?
If you click away and there is no more collapsed box at the bottom of your 3d viewport, you can go to Edit - > Adjust Last Operation. It will bring the options for tha last operation back when it is no longer on screen. As soon as you perform another operation the options will change to that operation though.
Simply put: No. You only can get back these options like in the answers above mentioned. Blender does not use the system of adjustable primitives like other 3D spftware. You can add a primitive of course, but after adding, it's just a simple mesh object. There are exceptions, like in the Archimesh addon, but the standard behavior is as mentioned.