Whether it is possible to draw weldment profiles(SLDLFP File) other than (different section) default profiles in Solidworks?
Yes, the default location for the files are C:\Program Files\SolidWorks Corp\SolidWorks\data\weldment profiles. There you can open a file then alter it and save it as a new name. eg change angle iron 35x35x5 to 35x35x3. Or even make a new folder with custom shapes.