Harry, if anyone replies to you with a definitive 'yes' or 'no' immediately give that comment a side eye. Immediately.

OLED, just like LCD comes in a range of quality. Think good, better, best. Knowing Apple, those first two categories don't count. Samsung's top of the line SAMOLED panels for phones have been ranked by Displaymate as the top panels for phones for a number of years now (that includes LCD panels). Nothing has changed this year.
Source. TLDR excerpt:
"
The Best Smartphone Display
The Galaxy S8 is the first in a new generation of OLED Smartphones that have a Full Screen Display design. It has many major and important state-of-the-art display performance enhancements, features and functions, with mobile OLED display technology now advancing faster than ever. The Galaxy S8 is the most innovative and high performance Smartphone display that we have ever lab tested. So the Galaxy S8 becomes the Best Performing Smartphone Display, earning DisplayMate’s highest ever A+ grade." -Displaymate
Dollars to doughnuts, Apple is getting these panels. Couple that with Apple's under the hood voodoo, and I'd be willing to bet the OLED iPhone will take that Displaymate crown. That's not to say there aren't relevant trade-offs of OLED vs LCD. We're at a point now with screen tech, especially at the top end, where saying 'much better' becomes moot. It's pretty hard to find a flagship device; heck even a mid-tier device, with a bad looking display. iPhones have a great looking display now. They will have a great looking display when the new phones debut. Should be the least of your worries.
Apologies for the length.