Then please contribute something that is relevant and helpful to the OP.
I'm not the one posting irrelevant distractions here.
There's no easy solution within Lightroom to this problem. Probably the best approach is to export as an uncompressed TIFF, then load into an image editor, eg Affinity Photo, that shows what size a saved(exported in AP's case) the image will be at different compression settings or changed dimensions if it's impossible to achieve an acceptable result with file compression.