Some actual safety tips for teenagers:
1. Have proof they're a teenager first. More than just a picture, have a video call with them.
2. If you want to meet up with them, have your parents or a trusted adult come with you. Even if they are a proven teenager, its still good to have supervision in case any issues happen.
3. If you are talking to an adult, and they start being sexual in any way, you run the fuck away. It doesn't matter if they're 40 or 20. An adult inherently has a power dynamic that teenagers do not. And its up to the adult to act responsible about it. There's exceptions of course, if you're 16 and dating an 18 year old, that's not a problem, we're not talking about that.
4. Being in a server with adults or ran by adults is not inherently bad. Talking to adults is not inherently a problem, and will likely happen in any number of Discord servers. It is only an issue when they are acting sexual and show predatory behavior.
5. Look out for grooming behavior. It can be difficult, because at first it seems like innocuous behavior, like complimenting or giving gifts. Especially if you feel lonely and have low self esteem. And groomers actively target people like that.
If they start trying to isolate you, talk sexual with you, state they depend on you for emotional needs, blame you for their own actions, try to be secretive about the relationship- Then you need to talk to people you trust, block the perpetrator, and call the police on them.
6. If this does happen to you, remember this: It is not your fault. Even if you didn't listen to a single thing listed here, it is not your fault. It is the fault of the adults who knew better, and didn't care. It's not your fault.