I did this when we moved from a 3 bedroomed house to a 2 bedroomed small apartment.
I hired a skip from a company that recycles as much as it can. I threw out all the rubbish. I left plant pots by the recycling bin and people picked those up. Even some stuff in the skip people picked out, often within minutes!
I gave away decent stuff for free either to friends, Facebook marketplace or charity.
I went through everything! We now only have what we need and use apart from a couple boxes of sentimental stuff.