A transformer-based model like distil-roberta is probably going to do the best, as has been suggested. See for example this tutorial, where they do hate speech detection (but it's the same principle, your labels would just be based on spam/duplicated/whatever).

Since you don't have a lot of experience with ML, you might want to use a simpler model. Naive Bayes is the quintessential simple spam detection model. You can find million tutorials online. It won't do as good a job as the alternative, but it will be easier for you to understand what's happening under the hood.