There is 2wd, rear locked or not by selection from the dash.
There is 4 wd H, same selection for the Rear.
There is 4 wd L, same selection for the Rear.
There is All wheel drive, uses a different Transfer case version. separately selectable. (A) on the selector switch if you have it.
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All vehicles are not set up the same. It depends on the year, level and options.
All wheel drive is a variable 4wd system or it would not be all wheel drive.
Wet/Snow Mode is not bringing in 4wd by just that selection. You could lose control to easy if thst were so, in a turn at higher speeds.
To support this, Rear lock up is auto released above 25 mph by speed sensing and will re-lock at 20 mph or lower. Only mode Rear lock will hold is in 4WD Low at any speed, for a reason. When off road and slow crawling in first gear over obstacles and lose that grip unless you select to do so by, dash control. One rear wheel hanging in the air doesn't help much when unlocked.
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All years and model level options are not the same for these features in combinations.
You have to stop disagreeing with the facts an learn what your options are and how they can be used.
If you do not like what you have, you have the wrong vehicle options or don't understand what you have.
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The trucks have to have these combinations to compete in the marketplace as well as fit the Owner desires best they can, even if some of the features are never used.
The combinations are set up to be as safe to use as possible unless the driver uses a combination that is not intended to be used for the conditions. Driver has a responsibility not to do this.
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To offer the point, I Ilve on the side of a Mountain. Drive Way exits onto a steep part of the road.
I have to make a right turn and then a sharp right Curve all downhill. Using full time 4wd is a big problem from both front and rear wheel spragging for sharp turning against up coming traffic I can't see. any time, especially in slippery road conditions and getting out of the drive way from a stop.
The 4WD or the Rear lock up cannot be instantly turned off because it is mechanically friction locked until the vehicle is going in a straight line to relieve that friction lock-up ( even turned off).
I have to be very careful when the road is ice covered not to use a mode that locks up or make steering and Braking impossible on a 5000 lb+ truck under these steep hill conditions. Been there for over 60 years and several 4wd trucks, and know better.
You have to learn what you have and use common sense for conditions of use.
its your responsibility. The drive modes do not relieve you of this, only help out when used wisely.
Good luck.

 

it also modifies shift points and throttle response in “slippery”.

 

Since this is my first 4wd vehicle (I normally had awd) since I dont have 4A and I have ESOF can I switch to the modes that turn on the 4wd while im driving? Or does the vehicle need to be stopped? Also for that matter when it comes to switching to 4wd and not using the drive modes can I turn on and off the 4wd while driving?

 

ESOF = Electronic Shift On the Fly. so yes.
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4WD L, no. Must be stopped, Trans in N, foot on Brake.
This mode will not be allowed unless these actions are all, present at the same time. The gear ratio change is too great to allow and would be a danger for accident and driveline line breakage.
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Normally 4wd H has no relation to the modes unless some Year and option is in Play.
Electric rear lock is also independent.
Do not run in these modes unless at lower speeds and surface is slippery enough to allow >some< wheel slip while moving because wheels, side to side, are locked together and try to revolve at different rates, in a Turn. Steering become harder out of straight line moving more than a few degrees on dry road due to the lockup in thr front and in the Rear .......>if locked independently<.
Year 2018 is open to all modes and combinations.
Good luck.

 

Yes, you can switch driving modes while driving. You can switch between 2wd and 4wd while driving. You can switch driving modes that go from 2wd to 4wd and vice versa while driving. You can do all those things you asked about... while driving.

The only difference between selecting 4wd with the 2wd/4wd selector and using a driving mode to do it is that the driving modes that use 4wd will also change the throttle response and steering sensitivity to be better suited for low-traction situations.

 

I had a 2021 STX 2WD. Slippery mode was great for rainy days. Keeps the *** end from slipping. I have a 2024 FX4 4x4 now. Slippery mode by default engages 4H. I turn that off unless there is standing water on the roads. In 2WD it still keeps the *** end from breaking loose. In my case, I do not have 4A. If I did I’d probably, as the last poster said, “let it rip!”