Probably too much to hopeful, but it’s always been on my wish list.
Say you want to set a net to a net class that uses a wide width. This is to carry high current.
But, the same net has segments that carry negligible current. Or, maybe you can only wire to the pins of a component with a narrower width, but you want the trace wider for a long run to a connector or other component.
What I’ve done in other tools is route the wide tracks first, then change the net’s class to route the narrower widths.
Is that the recommended practice in Kicad or (wishful thinking) is there a way to assign different segments of net to different net classes?
KiCad does not require tracks to use the netclass width. Which means you can simply manually select whatever width you want during routing or even later.
Another option would be to introduce a net-tie which gives you two nets one for the thin and one for the thick trace. In KiCad net ties are currently only able to be made with symbol/footprint pairs where the footprint uses pads. The latter realistically restricts it to an outer layer (it can be done on inner layers but is quite buggy). Once net-ties are first class tools (expected with version 6) I would argue this to be the proper way to do it.