Not any more.
Salt water especially has to be attacked within a minute or two, and even that's a bit long to hope for complete success. But something is better than nothing.
No, hand sanitizer, or anything with any kind of impurity, is exactly what you're trying to get rid of. 90% isopropyl alcohol is best, 70% is okay if you don't have any 90%, nut pure alcohol with nothing in it. (90% means 10% water, but even 100% alcohol is about 1% water until you open the bottle, then it absorbs water from the air and goes down to 98% on a dry day to about 95% on a humid day. (Which is why you never find 200 proof drinking alcohol - that's 100% and it's impossible in the real world.)
The S8+ is supposedly water resistant, but if you got water into it there\s a leak somewhere, so the alcohol can get in through the same leak. Drain it, fill it with alcohol (swish it to force the alcohol into the leak), twist and shake to use the alcohol to wash off all the salt water impurities, drain, repeat 2 more times.
Alcohol won't damage the screen. I've never tried it on an oleophobic coating (I don't even know if the S8+ has one), but I wouldn't count on that lasting too long in normal use anyway. And that's about the only thing the alcohol can affect. All it does to glass (which is the only screen material the alcohol comes in contact with) is clean it. And the battery is sealed (it has to be) so the alcohol won't affect it.
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