This is a very valid and smart concern to have. But the scary commands all start with “sudo”, which gives everything you type in root access. Other than that linux is very secure and idiot proof as long as you read what the commands do. For software linux is way more secure as gone will be the days of rummaging through dodgy sites for installers. Instead you just open up software center and find the app you want and it will be installed straight from the official upload. The repos software centers have are customizable so you can add and remove them. Instead of checking if the installer is secure, you check if the repo is secure on the rare case you add a new repo.

I mean a popular app distribution is flatpack that ships apps like steam and blender and whatever in a sandbox with access only to resources they absolutely need access too. To the point where you need to allow the apps to get access to another drive even. Just to make sure nobody will inject ransomware through the blender default cube I guess.