Can I update iPhone from 18.4.1 to 18.6.2

Generally when updating your device will update to the highest version currently available that it will support, or it will just say it is up to date (and can't go any higher) and won't install anything. You cannot select which version other than those offered. Normally there will be only one. We updated my wife's 16e recently that was on 18.7.1 and it was still offering updates to iOS18 even though iOS26 had been out for several months. She could either update to 18.7.2 or she could update to 26. It offered both.

Check your Software update options and it will show what is available for your device.

Settings > General > Software Updates

You cannot pick and choose an iOS version. What you get is Settings > General > Software update > [All options are available here]

An example image is given below.

Definitely not 18.6.2, no.

If you can still update to 18.7.x it will be on, probably at the bottom, of the page, in Settings, General, Software Updates but I think you missed the boat on that. You needed to be on 18.7 already.