For many travellers, yes. Current phones are strong on wide landscapes, people, shipboard scenes, video, panoramas, close wildlife and scenes with difficult contrast, and their processing handles bright snow against dark rock with very little effort from you. For sharing online, photo books, normal prints and your own memories, a good phone is more than enough.
Where a phone falls short is distant whales, birds in flight, low-light wildlife and anything you want to crop heavily. Digital zoom degrades quality fast, so stick to the phone's true optical focal lengths and avoid stretching it.
If you're travelling phone-only, the kit that makes it work is small: a protective case, a secure wrist or body tether, a power bank, two charging cables, a lens cloth, a waterproof pouch, and enough free storage cleared before you leave.
The tether is the item people skip and regret. Around Zodiacs, railings and wet landings it's the difference between a dropped phone and a lost one, because a phone that goes into that water is not coming back.