Since landing pages is a page that is dedicated to converting your visitors to potential customers, you should not post landing pages carelessly to any platform you can post links. If your landing page is where you sell medical products, you can post the page URL on some platforms like Facebook groups where people are seeking such related products or services. This is why when you want to advertise on platforms like Facebook, Instagram, Twitter, etc. they will ask you to choose the category of people that surely have an interest in your product.