Yes I've printed at nearly 400 C as an experiment. I've successfully printed an Icarus fan duct in GF-PEI for example. It's possible with the Dragon hotend and a 60 W heater, probably with a 50 W heater as well. There are other hotends that can do it too but ensure you use one that is rated for the temp as well as using a thermocouple rated at 500 C (a K-500 thermocouple).
One thing to remember though you will likely need dual hotend fans to transfer away all the heat from the hotend efficiently else you will get heat creep and clogging as a result. What I did was print a special mount with one fan in front (like standard Icarus) and one in the rear then use the top right plug on the PCB to power that extra fan (so it was always running), after that it ran longer prints fine at 385 C.
Printing PEEK or PEI for example is very difficult but it can be done, definitely not for beginners. You need high bed temps, high chamber temps and will probably have problems with bed adhesion and warping. I would also use a one perimeter draft shield around the printed part to keep the heat enclosed as much as possible (see video below). These printers aren't really setup for it though, the recommended chamber temp is difficult to reach. You could do so with a PTC heater but if the temps get too high your stepper motors won't be happy. But 2 or 3 hour prints should be fine as long as you can get bed adhesion. Print on glass using Nano Polymer as adhesive.
I don't recommend it but it can be done. Good luck.