There are many alternatives to Microsoft Lens for iPhone and since it's discontinued a lot of people are looking for a replacement. The best iPhone alternative is Pocket Scanner. It's not free, so if you're looking for a free alternative, you could try OSS Document Scanner or Google Lens. If that doesn't suit you, our users have ranked more than 50 alternatives to Microsoft Lens and many of them are available for iPhone so hopefully you can find a suitable replacement. Other interesting iPhone alternatives to Microsoft Lens are CamScanner, Open Scanner, Preview and Genius Scan.
Office Lens is adapted to many platforms, but if I talk about iOS, I choose Pocket Scanner.