i have had good luck on craigslist, just have to wade through the scammers and lowball commandos lol

a dealership may be interested in your 2018 honda, the toyota dealership where we bought our '19 RAV4 has offered us more than we paid

some folks have good luck with facebook marketplace 

Craigslist.

Just something to consider is that what you owe on the car is not necessarily what the car is currently worth. So you can't expect to get what you owe on the car. Try places like Carvana or Vroom too, or yeah try selling it yourself but you should keep your expectations for what they are going to pay you realistic based on the actual value of the car. Not to say their numbers are exact but just to see the values try kbb for example to see what the going price for that car is.

Craigslist, or a car dealer would be my top two choices. I keep getting emailed offers from a Ford dealership my parents bought cars from trying to buy my 2017 Mustang for $18,000 and I owe a bit under $14,000. They want me to buy a brand new Ford, which i have no interest in. I would hang onto your Civic unless for some situation you absolutely need a new car. Whatever hike they give you for the car you have will just go onto the price of whatever you buy next if you sell at a dealer. I saw a 2020 F-150 at a dealer with 100k on it, regular cab, short bed with a V8 and 4×4 nothing else and the dealership wanted $21,000 for it. 

Personally, I refuse to pay these outrageous sums for cars. It makes putting remanufactured transmissions and engines in an old car you already own much more appealing than junking them. 

Unless there is a good reason you need to sell, I recommend you hold onto your vehicle.

That being said, if you need to sell go through Craigslist, avoid Facebook Marketplace, also try getting offers from Carvana and Vroom.

I had excellent luck with Vroom selling a car recently. Their appraisal was $8k higher than the best dealer offer.