All EV's still use some fluids. These fluids degrade over time due to friction, wear, temperature cycles, air humidity etc.
Same happens with solids like brake pads, tires, struts, bearings, bushings, wiper blades etc.
All cars require maintenance, that includes EVs. That includes Teslas. That includes Model 3.
When mechanical part fails, those require replacement. In case of fluid degradation, those require replacement.
This includes:
Brake,
Coolant,
Drivetrain,
and compressor
OIL or LIQUID
Most can be counted as "lifetime" fluids. But vehicle's actual lifetime is longer than manufacturer defined lifetime.
For example, BMW has "Lifetime" gearbox oil and does not recommend any oil changes. But it has been proven that
oil gets excessively contaminated after 60 000 miles, which speeds up gearbox total failure. It has been proven,
that changing oil against manufacturer's recommendation will prolong lifetime of the whole transmission.
Compressor oil doesn't degrade enough and/or it has not been proven, that changing oil/refrigerant/dryer will prolong
system lifetime in any meaningful way. PS: Tesla Model S/X has dryer replacement in the schedule, that is unreasonable.
Coolant does degrade over time. Fluid is excellent for few years, then it is "fine" for another few and it is not good around
the time when warranty runs out, somewhere around 60 000 miles. It doesn't break anything but it doesn't have enough
protective chemicals that prolong the life of components coolant touches.
Brake fluid degrades mostly due to air humidity. It's excellent for 2 years, then it's usually fine for another 2 (applies to modern
cars incl Tesla) and after 4 years it is not good. It doesn't break anything but it is contaminated, which also contaminates
components in the system. And it will not handle very high braking actions for long (racing or going down the hill with
limited regen for example).
Drivetrain oil degrades due to wear in the reduction gear, air humidity and also some thermal cycles (applies to EVs as well)
Initial degradation is very fast. During first year there is a lot of contamination. This is due to parts break-in-period.
Model 3 has drivetrain oil filter, which likely takes care of that initial contamination problem (abrasive stuff is filtered out).
But the oil itself will still degrade over time. Even if no oil replacement is done, drivetrain will likely be fine for very long
period of at least 5-8 years. But it's true, that changing the oil after years of use will prolong lifetime of components in the system.
To sum up. Brake fluid degrades the fastest. Then coolant fluid and drivetrain oil. Compressors often handle a decade without
any service and changing the fluid in between has not been proven to prolong the life.
If manufacturer doesn't state anything, I'd recommend to change all three no later than right before warranty runs out,
therefore around 60 000 miles / 100 000 km.
Looking at official Model 3 manual, brake fluid replacement 2 years, coolant 4 years (or 50 000 miles).
If Tesla does not require drivetrain oil change, one can ask them to do it.
Like I said, I'd recommend changing drivetrain oil and it's convenient to do on the second service (50 000 miles), with coolant.
In case of AWD, both drivetrains of course. And in case of Model 3, oil filter as well.
PS! One more note. In case of EV with no oil filter (Model S/X, Leaf etc), it might be more reasonable to do first drivetrain oil change
on the first service mark (25 000 miles, 2 years) and the next one on the third service (6 years).