Ram is not an operating system issue as I think you are using it. You might find Crucial’s explaination on RAM worth reading - the link is HERE.
Your question is similar to another users post that I replied to - you might find my reply applicable to yours as well. The link is HERE. The article linked in my reply covers memory as well and worth reading. As the author notes, sample libraries like the Berlin Strings library from Orchestral Tools recommend at least 32GB of RAM for that alone for best performance. At the end of the day, the amount of RAM you’ll need for digital audio production will depend on how many plugins and sample libraries you regularly use, but your description of 85% usage would be a flag for me that more would be desired and worth the additional money if you are going for a new rig.