Tag Lines

I’m learning to use and set up the drop shot rig. The rigs that I’ve seen online usually show the main line diameters and lengths down to the tippet ends. However, other than suggest the lengths of the tag lines and where to place them, I’ve not seen suggested tag line diameters. Should the tags be equal or less than the attaching mainline diameters or is it fly size dependent? Would appreciate your help. Much thanks
Edit: My question pertains to the situation when the tag ends of blood knots or triple surgeon knots are too short to be used. George Daniel suggested to tie on a tag onto the running line with a clinch knot. It does make sense to use the same diameter for the new tag as the original however.