Install to a different drive and check how much space it is using. If it is using too much, then use the content manager to delete some stuff that you can do without. Once you have the size you want either rename the folder to stop MSFS deleting it or make a backup copy of it. Then uninstall MSFS totally. When you reinstall point at the 250gb drive then close the programme down. Copy what you have into the folder on the new drive. This should sort it for you.
There is also a way to move the MSFS folder. This would save you uninstalling it etc. It is not something I have done so cannot help there. There should be information online though.