Virtually every geospatial format uses longitude latitude order. WKT, WKB, GeoJSON, KML, Shapefiles, FlatGeobuf, Geobuf, you name it. Your data in PostGIS? Longitude, Latitude. Google Earth? Same.

If you're storing data in a standardized format, odds are it's longitude, latitude. If your starting guess is the opposite, you will almost always be wrong.