Not too long ago I had an iPhone, in which I had bought and installed a mobile game (Bloons TD 6). I recently switched to an Android and really wanted to play the game again. I tried looking if there was a way to transfer the game from my iPhone so that I wouldn't have to spend another 5 dollars, but I couldn't figure it out. I don't know if I'm just not doing something right, but if any of you know what I can do, if anything, I would appreciate it.
No, you can't.
It's not possible to transfer a game installed on different operating systems. The main reason is that, even if the game is the same, its files are incompatible. And also because if you purchase a game it can be used only on that specific platform, all digital content is tied to your iOS/Android account.