It seems that Adobe InDesign posses export function to JPEG format for some sort of preview purpose, accessible through the standard program menu. It seems this is the only way how to achieve idml to jpeg conversion, as no other program supports InDesign formats.
Convert InDesign Markup Language document to JPEG bitmap image format.
We found 2 software records in the database related to .idml to .jpg file format conversion.
Microsoft Windows software - convert idml to jpg on Windows
Professional desktop document publishing software from Adobe
Convert from idml 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 idml to jpg. 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.
Apple macOS / Mac OS X software - convert idml to jpg on OS X
Mac version od Adobe's popular document designing and publishing software