In Acrobat, try Save as... Reduced size PDF or Optimized PDF.
How much you can gain from this, highly depends on the content of the file and your settings.
To reduce the size twice... why not, sometimes possible...
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To answer your specific question, you most effectively reduce PDF file size as follows when you export your PDF file from InDesign as follows:
(1) Choose export options that downsample images to lower resolutions. For example, the predefined print-oriented export options (i.e. .joboptions) downsample images to 300 dpi for images over 450 dpi. This is perfectly fine for PDF files being printed on high quality devices or that may be viewed on large 4K ultra high definition monitors. However, for less critical printing and/or viewing on lower resolution monitors, 150 dpi to 200 dpi may be adequate and could dramatically cut PDF file size.
(2) Choose export options that use lossier compression for raster images. Typically, the predefined export options use Automatic (JPEG) Maximum quality compression. Changing the Image Quality from Maximum to High or even Medium may yield acceptable results, but you should experiment.
(3) Combination of (1) and (2) above.
(4) Make sure to check the Compress Text and Line Art option. This option is non-lossy and can achieve significant compression for content that is not raster image-based.
(5) Check the Crop Image Data to Frames option. This option only includes the part of any images used by your InDesign document that actually are visible on output due to cropping within a frame. Note that this option can backfire on you if you repeat the same image multiple times in your document with different cropping.
If you properly export your PDF file and make prudent use of the points listed above, the tools available in Acrobat will be of minimal benefit to you in reducing your PDF file size with the least amount of lossiness.
Of course, if nothing really reduces the size of the PDF while maintaining adequate quality, you just might want or need to consider simplifying the content itself. Ultimately, you can't legislate a particular PDF file size without taking into account the overall quantity as well as quality of the content and the output!
I wouldn’t do that, if I can change the export parameters from Indesign. Dov’s counsel is best. You need to optimize the export parameters for a fair trade off of quality and size. Please bear in mind that very often a maximum quality is not needed. Lossy compression is only bad, if you reuse the work for further modifications.