If it calls for regular, you can use regular. My 2020 Honda Accord 2.0T uses regular.

If 87 is recommended in the manual, for sure!

Stick with regular (87 octane) gas if that's what the manufacturer recommends. If the car isn't designed to take advantage of higher octane you'll just be wasting money on premium.

Normally, the air-fuel mixture in the cylinder is compressed (during the compression stroke), and the spark plug fires at the top of the stroke to ignite the fuel.  But compressing a gas itself raises the temperature of the gas, and if you compress it enough you can spontaneously ignite the fuel (this is how a diesel engine works without spark plugs).

Turbos and superchargers pre-compress the air before it enters the cylinder in order to increase the oxygen available for combustion.  The problem with using low-octane fuel in older turbo cars is that at the higher pressure, you can get spontaneous ignition before the cylinder reaches the high point of the compression stroke (ie, pre-ignition), which causes knocking and can eventually damage the engine.  You can overcome this by using higher octane fuel, which is less prone to pre-ignition.

That is why most high-compression engines, including most turbos (like my 2018 WRX) and even some naturally-aspirated engines (like the hemi V8 in my wife's Grand Cherokee), specify premium gas (91 or 93 octane).  However, most modern, computer-controlled, cars are able to automatically adjust the air-fuel mixture to avoid pre-ignition when using lower octane (87) gas; it comes with a loss of a little horsepower and MPG, but it won't damage the engine.

Seems like most turbo cars I have seen recently recommend premium fuel in the owners manual, though they state that you can use lower octane fuel if you have to.  I have never seen one actually recommend 87 octane for a turbo engine, but I don't see why not.  My guess is that if you ran 91 or 93 you would get more power and MPG, but that the difference isn't enough for the engineers to recommend it.  If the difference is minor, it would just be a waste of money, but it wouldn't hurt anything if you wanted to test it out for yourself.

Back in the old days, when cars had carburetors and turbos/ superchargers, you had to put premium in them, or the engines could destroy themselves via fuel detonation, which is commonly called knocking. They had no computerized fuel injection or variable valve timing to help reduce this. My 1979 Pontiac Catalina has a 301 V8 is carburated with an 8.5:1 compression ratio and it's naturally aspirated, so putting premium in my car would be an absolute waste of money. The engine can't adjust for the higher octane, and it doesn't have high compression or forced induction to raise the pressure enough to cause spontaneous fuel ignition.

In a modern turbocharged engine like the EcoBoost Mustang's engine the compression rationis 9.5:1 and they have forced induction. Sensors in the engine monitor the compression stroke constantly for pre-ignition and will adjust valve timing to either back off on the amount of air getting sucked in, or they can add additional fuel to cool the air on the compression stroke, both are options. None of this can be done with an old carburated engine. With those, air gets sucked in, pulling fuel into the airstream at a fixed ratio, determined mechanically by screws, then it gets burned in the engine. Valve timing is constant, with no advance or reduction in timing based on load. Low Octane gas needs removed or it will destroy the engine because it can't be compensated for. Your Kia is almost certainly fitted with the same sensors as the EcoBoost Mustangs are, so it will tolerate both high and low Octane gas. You will likely notice a power difference with high octane fuel, as it allows the turbo to work to its full potential, cramming more air into the engine so the igniting fuel does so more explosively. 

You can't really hurt your modern turbo engine by putting high octane fuel in. Putting fuel with lower Octane than that recommendation will more likely cause problems.

Taking the Civic sedan and hatchback from 2020 as an example, the sedan with 174 hp from the 1.5T uses regular gas but the hatchback with the same engine but 180 hp recommends premium gas meaning that you should put premium but you can also get away by putting regular. If the car requires premium gas, then u must do so. Stick to what they say.