All the helmets designed for F1 2017 and F1 2018 don't fit in F1 2019. The helmet texture mapping is different and the gloves and shoes are in different file as the wing and the protection of the visor. The com helmets has disapeared expect for Senna and Prost so if you want you have a personnal helmet with your personnal sponsors on it you will have to replace one of them (but i don't know if this two helemt are present in every game version because i have the legend one)...
I hope someboby can extract the 3d shape of the helmets(with wing and visor and all the stuff) to be able to make personal helmets.
For information, I won't do classic helmets and suit for this game for now but i will continue to make them for F1 2018.