On LingQ, for speaking you can hire a tutor or attempt to find someone as a partner (may not have good luck on the latter). Or try some of the suggestions SergeyFM gave for this. Otherwise you can practice yourself. Just try to start saying things. Describe your day as if you were telling someone. Then look up how it might be said after using DeepL. Or write it out and share it on LingQ writing exchange.

For writing if you click on "Community" section on the website (how you get to these forums). You'll see "Forum", "Challenges", "Writing Exchange", "My Profile", "Contribute". Select writing exchange. You can do some writing and submit it. Someone will give you corrections to your writing or suggest different ways of saying something if it's not quite right. You can also import these as a lesson which is useful. It's a really nice tool to practice with. Of course, it may be dependent on the language you're doing. If it's a widely used language you'll likely get someone to edit it within a day.

You can't find it because there's nothing of this sort to speak of.

I wouldn't say LingQ is the place to learn to speak and write. The methodology is based on the input-approach and LingQ excels in this.

LingQ has helped me a lot to be able to understand a foreign language, but as a result my skills are very unbalanced. It's furstrating at times, being unable to express myself while fully understanding what someone's saying.

Therefore I would recommend other services like iTalki or Lingoda for speaking.

As for writing, one just needs to write more, and for me that's a constant struggle.