Can’t you technically install or side load apps on iOS even if not jailbroken?

[max2]

Or am I wrong?

 

[ruslan120]

Yup. You can use developer features to install different applications that aren’t in the App Store.

 

[TiggrToo]

Or am I wrong?

"Technically" you can. In reality you don't.

You can apply for a Developer license and deploy your own (or corporate) written apps, or you can skip the license and deploy an app with the proviso you a have to reinstall it every 7 days.

As for third party apps - no. No sideloading is allowed outside of Jailbreaking.