(I've been researching this for hours and have yet to find a straight answer, so at this point I don't care if this gets marked duplicate.)
I'm a complete noob to QGIS. I have a floorpan SVG that I cleaned up in Inkscape and exported as DXF. The coordinate system of the DXF is in point space and I have the (lat,lon) transformation of the 4 corners. When I import the DXF as a vector layer, I don't see any way to set a custom transformation to WGS84. Ultimately I want to be able to export the geometry as Shapefile or GeoJSON.
Most of the other responses I've researched are either out of data (plugins that no longer exist, tutorials wherein the instructions are out of date, etc.) This shouldn't be this difficult.