I'm not sure, as most legal and authorized platforms charge for accessing manga. But be careful with free apps, as they might be illegal or of poor quality.
There are several dedicated BL manga websites. For example, Mangago and Kissmanga have a decent selection. But be careful as some of these sites might not be legal or safe.
Some libraries might have digital collections of BL manhwa. Also, you could check out social media groups or forums dedicated to BL manga, where people often share recommendations and links to where you can read them. Just be cautious and follow the rules and regulations of the platforms.