I'm not promoting underwater use or regular submersion of your phone ... but ... I have submerged my S8+ and my S10+ MANY times, and have - very often - gotten it very wet, to the point that the little warning indicator notification shows up saying not to plug in the charging cable because the USB port detected water and needs to dry out before you plug it in again.
That said, I have had NO issues with water resistance on either phone, or my Galaxy Watch (S3 Frontier). So far, both have been "as advertised" and I am extremely satisfied with the water resistance of the devices. I regularly wipe any/all of these devices down with damp cloths, and even take my phone in the shower in the mornings sometimes if I want to take a long shower and look at my emails, calendar, etc. and plan out my work day. I'll let it get plenty wet without reservation.
Just throwing that out there for anyone looking for real world experience with dunking, submerging, washing, flooding, etc. any of these devices with water ... including my pool.