"Quality links" is a subjective term. At one time not long ago Web 2.0's were considered "quality backlinks", today, not so much.
A quality backlink today is one that is contextual and on a real website. The content also needs to be relevant to the page that it links to your website. Many will get all obsessed with high DA , TF or DR backlinks but that really doesn't mean all that much. What matters most is if the website has a clean backlink profile and more backlinks the website has, the better it is.
You can buy some PBN links, but usually any place you can buy PBN link will not be around for long. It will eventually get deindexed. Guest posts or niche edits are the best route. Again you can pay someone to create these for you. Or you can do the outreach yourself by contacting webmasters and offering a guest post. Some will give you an opportunity to post for free but many will charge you a fee for a backlink. You can do the same with niche edits by looking for broken links or having information that would benefit the other websites readers.
To fine places to post you can search for blogs in your niche or related niches and contact them. Be prepared, it is a lot of work.