Earning links to your website is called link building. This is a matter of offering interesting content. If websites and portals related to your field contain a link to your website, Google will see your website as important and your Pagerank will improve.
Advertising on portals can generate additional website visitors and therefore turnover because portals are often easy to find in Google. The disadvantage is that advertising in good portals is often expensive and that your competitors are also listed on them. If you can earn a link on a portal, it is often a “no-follow” link and will not have a positive impact on your ranking. So in the long term it is better to ensure that your own website is simply the most interesting, so that you do not need the expensive portals.
Online tools allow you to see which sites are already linking to your website. Also use this tool to see backlinks to your competition’s website. You might also be able to earn a backlink on those same sites: Try semrush.com or ahrefs.com/backlink-checker
Disavow spammy links
Participation in link farms or paid links to improve page rank is not allowed by Google. This also applies to excessive links in blogs, forums, etc. Never link back to other websites in exchange for a link to your website. But it is possible that, for example, the competition places spammy links on link farms to your website, causing Google to give you penalty points. In that case you can report it.