Thank you Richard.
Realizing some textures for the Fouga would not displease me.
But ... here it is the payware version Azur Poly whose paint kit is made for Blender.
A program that I don't know how to use.
If I make a texture, it will be for the free Restauravia version which has a paint kit for Photoshop.
For a German texture, there is already that of Jan Kees for the Restauravia version (see above) and for the Azur Poly version, a camouflaged version has just been published on Flightsim.to.
https://flightsim.to/file/28223/azurpoly-fouga-magister-german-air-force-aa-015