Android and IOS app platform suggestion

Hey everyone, I’m going to develop an app for android at first but I want to make the same app in IOS as well in the future, with the two to be compatible with each other (Social media app).

Where do you suggest to write my code , what platform should I use to do so?

I’m very good with Java if that helps but my priority is to write with the most modern way possible and the one that has a lot of info on the internet through tutorials etc.

I read about android studio using java but what will I do for the IOS part. I don’t want to start all over again.

Thanks in advance