Since there's only 2 cig ports, wanted to see if there would be any issue if I got splitter (with either 2 or 3) and using each of those ports with 1-2 USB's. The one inside the center console has 2 USB ports for dash cam and gf's iphone charger (it'll connect to carplay if I plug it into one of the car USB ports). The back cig port has a super fast charger via USB-C for my android. I need another cig port for a radar detector that I'm planning to get. (because I want to and besides the point)

1) Do the USB ports in the vehicle provide constant power? My dash cam has parked recording so it does require continuous power.
2) If I do get a splitter (example link below), would that be an overload and cause problems such as blowing a fuse? I don't know anything about power/electrical so please don't assume with your answer.

 

radar and dash cam should be hardwired. your car ain't no Uber!

 

From page 270 of the 2019 Lexus ES350 Owner's Manual for the 12V power outlets (cig port in your terminology) and USB ports:

So, neither the USB or 12V power outlet ports will provide the continuous power you want for "parked recording".

From page 269 pf the above owner's manual:

Well, if you can rely upon the 100W power specification listed for [mainland] Chinese made Yantu item then 100W maximum power consumption of everything you're going to plug into the splitter device plus the power consumption of the device itself will be within the maximum power rating of the 12V power outlet.

However, the real question remains is what is the sum total power consumption of all the devices you're going to plugin to the splitter device and whether the marketing propaganda of "Built-in Safe fuse and smart recognition chip prevent from over-current, over-voltage, and short-circuit protection..." actually works to keep the total power consumption of everything within the 100W device specification.

I personally wouldn't purchase the example device you've linked to for multiple reasons:

1. The "2 Smart USB Ports" capabilities description is dodgy. With some digging it turns out "3.1A total output" is 2.1A for one port and 1A for the other port which puts lie to the "rapidly charge 2 devices simultaneously" claim. The dumb, "standard" charging rate USB ports built into the ES are rated at 2.1A charging rate for each of the 4 builtin USB ports. So at best, that device has no better USB charging capabilities than you've already got builtin to the car.

2. In reading over the Amazon comments, it looks like there's a 2.3 DC voltage drop across the device under approximately one half the maximum rated (100W) power load. For an input voltage of 14V only 11.7V is supplied to a device you plug into one of the splitter power output ports. Aside from the fact that's quite a bit of power loss [in the form of waste heat] in what is essentially a passive, dumb device, the relatively large voltage drop from the splitter device may result in plugged in devices not operating or operating poorly. (Electrical devices have minimum input voltage requirements and there is some variation in minimum voltages across 12VDC car power outlet intended usage gadgets.)

3. The power input/extension cord looks to be undersized or of poor quality for the 100W power rating. At half power, a power cord should not get hot as a comment mentioned even when coiled up. Requiring the input cord to be uncoiled (as a stated in a comment update) to avoid overheating indicates either the wire used was undersized for the device's power rating or poor quality materials were used.

4. Dipping into the 1 and 2 star comments yields doesn't work, works intermittently, fire hazard, blows vehicle fuze, induced static in radio devices, etc.

 

The link was more of an example of the general product rather that specific one but wowie, appreciate the detailed response!

 

So I got around to buying a for the dash cam but it doesn't come with fuse taps. It says that it requires 2 fuse taps and 2 5a fuses. Is there any real differences in fuse taps? From what I see, it seems to be the same but not sure what to look out for.

 

There are different form factors/styles/sizes of blade type automotive fuses so you need fuse taps and 2.5A fuses that match the same fuse "form" used in your Lexus ES. Unless I've errored on the parts lookup, my 2019 Lexus ES 350 uses in the passenger compartment fuse block fuses of the "mini fuse" type which appears to be valid for all 7th generation ES model years. So, you need a 2 fuse taps for mini fuses and 2 2.5A mini fuses.

Since you've stated "I don't know anything about power/electrical ...", I'll mention there is a correct way to install a fuse tap and incorrect ways. There are a multitude of "How to install fuse taps" resources you can find using your favorite internet search engine, one such example video that's informative and fairly short without much, if any, extraneous BS is . In particular, look at how to use a multimeter (or similar instrument for detecting 12 VDC power) to determine which fuse(s) supply always on 12VDC power, which fuse(s) supply switched 12VDC power (only powered when the car is in ACCESSORY or IGNITION ON modes), which side/pin socket of each of the fuse positions you're going to use that supply the 12 VDC power from the battery/alternator, and how to properly orientate the fuse tap and fuses for correctly fused circuits operation.

Also, with a fuse tap installed in an ES passenger compartment fuse block you won't be able to reinstall the fuse block cover. Since the fuse block cover has printed on it the information concerning fuse size and circuit protected for each fuse slot location, you need to think about how and where you're going to keep it for any future need especially in cases of service technicians need the information to diagnose/fix an emergency electrical problem.