Over 90% of clothing donated to thrift stores end of in landfills in exploited countries. Obviously I preach that you should wear your clothes as long as possible I mend them, but sometimes you just have to get rid of clothes.
I highly recommend selling your clothes for a dollar or two on an app like Depop or Vinted. For me personally, I see it as I would have given this stuff away for free anyways. You can make the price higher if you need to compensate for gas or materials. This way you know your clothing is getting into somebody’s hands for sure and still helping the people who need cheap clothes second hand. Most of the clothing I sold were much cheaper than my local Goodwill or Salvation Army.
In addition you can sell clothing that has visibly more wear that would get thrown away at thrift stores. Set the price at the lowest possible (usually $1) and explicitly state multiple times in the description that the clothing is visibly worn. Make sure to include all damage and do not make an attempt to hide it. Surprisingly people will buy this type of stuff. In my experience it actually sold much quicker than any of my other clothes. My best guess is that people are looking for clothing scraps to craft with as cheap as possible. 
Yes selling your clothing on an app and then not getting much compensation is a lot of work. It is much easier to donate clothing in one go to a store. However, as a consumer in a country where most of our clothing is made with highly exploited labor and dumping textile waste onto exploited countries, I see it as a responsibility to make sure I do not contribute to that

