ES upgrade from 6 to 8 - How to?

[Eduardo_Montes]

Hi, I tried to make the ES upgrade from 6.2.4 to 8.4. I found out that there are many not supported features in 8 version. E.g. missing tree a precision attributes in geo_shape data type, not supported possibility to define a multi-field within a multi-field etc. Is any handbook or tutorial for successful code upgrade using Elasticsearch? Or any version differences list?
Example for feature indexing:

{
    "properties": {
        "search_geometry": {
            "type": "geo_shape",
            "tree": "quadtree",
            "precision": "5m"
        },
        "search_point": {
            "type": "geo_point"
        },
        "geometries.geometry.coordinates": {
            "type": "float"
        },
        "geometries.rotation": {
            "type": "float"
        }
    }
}