Can CC LED driver be used to regulate voltage?

The answer is, no, a CC supply isn't intended to regulate voltage. CC supplies sense current and vary voltage to adjust to the target current. If you need constant voltage, it's the wrong tool for the job.

Large point-illumination LEDs assume constant current. If they don't include current limiting internally, you would use a CC driver for them.

Some LED strips (generally, the single-color type) that wire the LEDs in series also regulate on current. You would again choose a CC LED driver that outputs a specified current within a range of voltage (Series-wired LEDs have a minimum voltage and max.)

Other strips (such as RGB programmable ones) that wire the LEDs in parallel use constant, fixed voltage, and regulate each LED current locally to achieve the desired color / brightness.

Say you have a fixed voltage strip. If it has strict 12V input voltage and won't tolerate overvolting, a cheap-and-cheerful way to meet its spec is to use an LDO 12V regulator. Yes, the LDO will dissipate some power at max charge voltage (1.4W @14V worst case for your 700mA example.) You'll need a heatsink.

If your LED strip can tolerate slightly higher voltage you could then set the LDO a bit higher (+10%, or 13.2V) and thus reduce the LDO's dissipation to less than 0.5W worst-case. Very doable with a small heatsink.

Now, how about using DC-DC to achieve a fixed 12V? Any DC-DC solution used in automotive will need to be able to work both below and above 12V to accommodate low-battery condition (about 11V) through max charge (about 14V).

This is best handled by a buck-boost. Lucky for you, you can buy this pre-made as a 'voltage stabilizer', a module used to adapt strict 12V systems in auto applications. They provide a constant 12V regardless of the battery state-of-charge.

Now, is this stabilizer the most efficient? Surprisingly, probably not. Say the regulator is 85% efficient (and I'm being generous here) when it's in DC-DC mode. With your 700mA LED strip it will be dissipating about 1.3W all the time that it isn't in LDO mode. That's a very narrow window of voltage that doesn't tend to happen.

It's not any better, and possibly worse than, the LDO solution I've offered above.

As I understand, this converter simply makes sure that output current is at set level. It does not care about output voltage.

That's a DCDC (buck) converter that lowers voltage in order to keep current constant while driving an LED.

Instead of using ineffective (~85%) DC-DC, I though I could limit current (and voltage would be changed too?) with this converter.

An LED driver is a good choice here, but you may want to pick a buck boost driver or lower forward voltage string of LEDs as that buck converter requires the supply be 3v higher than the output and 14v is only 2v higher, so not going to work.

There are many strips that are dim at 8V and are bright at 12V and brighter at 14.5V with sufficient resistor heat dissipation for each segment.

If you prefer constant brightness, an active current limiter is all you need for which many designs exist.

Construction quality, luminous efficacy lum./W, power or W/5m reel and dominant wavelength are the biggest variables.

So for example, a 700mA at 14Vin for 10W 12V LED, would result in 9.8W output power

No, that would be 9.8 W input power. The output power would be 700 mA times the output voltage, so if that's 12 V you have$$12 V * 700 mA = 8.4 W$$

For an efficiency of around 85%, so you're not getting any improvement there, and that's assuming you could get a current source that would take 14 V in and output 12 V and 700 mA, which is doubtful unless you go to some kind of boost arrangement. And all this assumes that you have 14 V in and not 12 V such as when the vehicle is not running.

The converter you linked to will not got from 14 V to 12 V, see note 4 on the datasheet,

Output voltage will always step down 3 volts from DC input voltage.

So from vehicle voltage it couldn't drive an LED string with more than an 11 V drop and probably best for 9 V or less, so maybe 3 or 4 LEDs in series.

Constant current DC-DC power supply is best way to power LEDs if you worry about efficiency. 12V strips have resistors inside which is the waste of energy. For instance it is 3 LEDs in series with summary voltage drop ~9V and resistor. Calculate efficiency. Also voltage in automotive system may change in wide range, from 11.2 to 14.8V and constant current source better for device health.