There has been in-game characters for some of those in the past, but never in fighters. Heads of state don't fly fighters around. They travel in a heavily armed ship with a heavily armed escort.
Liberty had a liner once for it (When Del was Pres I believe).
The GRN|'s Chant du Cygne has been used on occasion to transport the king in-roleplay, but very rarely. He sits on Ile de France most of the time, while his children and the Duc project royal power in person on his behalf.
I don't think Rheinland has ever had a character dedicated or semi-dedicated to the Chancellor or Kaiser.
Kusari had/has the Satsuma, the Imperial Yacht, for the ex-Emperor.
Bretonia doesn't transport the Queen. Other dignitaries always go on her behalf of the event takes place off New London.