We will not block anyone from posting images like this - we can’t. Clients handle it differently.
As a poster you could add a content warning or a known hashtag like ‚nsfw‘ and apps would know to hide it.
If you fail to do so your account may end up on a filter list (e.g. primal hides a number of accounts by default). This could happen to you now.
Many clients only only show content from your followers and blur content in the global feed. This way you only see content from trusted users.