The latest rumor that Digital Chat Station posted on Weibo is about the upcoming OnePlus 13DCS specifically claims that the phone will get an IP68 and IP69 rating for dust and water resistance, and that would be a significant improvement over the OnePlus 12 which is only IP65 rated.
This is what the IP code says about that second digit (which relates to water ingress). If it’s a 5, like in the OnePlus 12, then the device is protected against jets of water. If it’s an 8, then the phone can be immersed in 1 to 3m of water for a duration that is generally expected to be longer than 30 minutes (this part of the standard is pretty flexible, so we won’t know the exact details until the handset launches).
OnePlus 12
The 9 rating offers protection against powerful, hot water jets, so the OnePlus 13 is highly water-resistant.
As for dust (the first number), you can’t go higher than 6 anywhere. The OnePlus 13, like the OnePlus 12, is classified as “dustproof,” meaning that absolutely no dust can get in.
Furthermore, the device is said to feature a micro-curved display, a battery with a capacity of around 6,000 mAh and an ultrasonic fingerprint sensor.
Source (in Chinese)