How to know what anchors to use on the ceiling?
Common ways to find out how the ceiling is constructed include ...


finding an existing opening, e.g. for a ceiling light, and having a good look in and poke around.
asking a neighbour whose house was built by the same building company at the same time
using a stud detector and wiring detector to see how uniform the ceiling is and location of any wires near the surface
drilling a small hole and seeing what comes out.


I believe many 21st century European homes have concrete-slab ceilings rather than traditional wooden joists.