I've deliberately, misplaced the top vertices of the mesh, added a subsurface modifier which smooths the curve, but as seen in the example it does have a jagged curve. Is there a which makes a smooth curve when I select the vertices, which then gives me the option to manipulate the curve/bend.
Thank you.
You have the LoopTools > Curve that allows you to curve a series of vertices: select the 2 extremities + a vertex somewhere between the 2, and right click > LoopTools > Curve. But you can't control the curve shape afterwards, the central vertex position gives the curve shape (of course another way would be to align the vertices then move up one of them with the Proportional Editing on).
I would use LoopTools Relax in the LoopTools add-on, and then a Simple Deform modifier on the relevant vertices as a vertex group.
If you choose Input: Parallel (all), the relaxing will also affect parallel loops, in this case the curves under the top curve. (choosing Input: Selection will only affect the selected elements)
Then select the vertices you want to manipulate and add them to a vertex group.
Finally put a Simple Deform modifier on the object, choose Stretch, enter the vertex group as a target, and manipulate the shape of the curve by changing the Deform Factor value
