It should be possible to export 3D models saved in SketchUp graphics format (.skp) to ISO-10303 STEP product data format (.stp, .step). Not all SketchUp files contain proper 3D models though, so it may not always work. The skp to step conversion should be possible in programs like 3ds Max or perhaps some dedicated converter.
Convert SketchUp graphics to ISO-10303 STEP product data.
We found 2 software records in the database related to .skp to .step file format conversion.
Microsoft Windows software - convert skp to step on Windows
A widely-used 3D animation application from Autodesk
Convert from skp file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned skp to step. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A converter for 3D formats