How to call multiples functions within the loop{ } and have them execute in parallel

arent they just variable ? or variable known to Ardruino ?

by test i mean if (msec > msecLedLst)

i am using UNO MEGA

yes it's a variable and used as a variable, by default set to zero.

so the very first time msec > 0.

but you suggest a problem and both msecLedLst and msecBellLst should be set to msec when run is set

i need to

if (condition ) {
ring the Bell()
Flashes the LEDs()
Servos Open gates()
all at the same time. the servo can finish their jobs after a while, but the bells and flash_LED() must go on.

Indeed sounds like a railway crossing. I did this a few years ago - but commented in german. It looked like this:
railway crossing with servo
Is this similar to what you want? I'll look if I can find the sketch and translate the comments. Maybe you can adapt it to your needs
At least what you need is a finite state machine - or better said 3 FSM, one each for bell, led's and servos.

I did it also with a small geared stepper motor what makes the moving much smoother:
railway crossing with stepper

Specify this requirement more in detail.

yes, as much as possible. When the condition is fulfilled, those functions need to be executed.

Try this

if (conditionTask0) task0(), conditionTask0=false;

What do you expect that code to do ?
What will the effect of the comma be ?

and the comma is used as separator.

I think that I will stick to

if (conditionTask0) 
  conditionTask0 = false;

which to me makes the dependant code block much more obvious, but each to their own

You still haven't written what it's really about. There have been some assumptions, but you have not reacted to them.

And I like to write compact code.

I started my development on Arduino Boards (Arduino Due) with exactly the same problem.
I decided to use a kind of cooperative multi-tasking based on state machines.

First I created a multi software timer environment based on measuring the time in loop() with micros().
Then I created a class for state machines with a run()-function switching the states. This run()-function is called by a software timer (= state machine clock). I have state machines with fast clocks (about 100 microseconds) and slow clocks (about 10 milliseconds) working together. Of course, the time consumption of a state has to be less than the shortest clock period (which is about 1000 simple operations in a state with the Due).

So all my libraries are state machines and build a cooperative multi-tasking.

The disadvantage is, that I cannot use Arduino libraries with functions of big time consumption in loop() (setup() is no problem).
But all my tests with preemptive multi tasking (RTOS on ESP32 and MbedOS on Nano BLE) had bad results. To complex with semaphore control or to slow for some of my tasks.

A structured array of function pointers and booleans will help.

That benefits no one. It makes your code harder to read and in a few months, it will even confound you. Come back in a year and even you will be trying to figure out what you did.

The compiler doesn't care.

If you really NEED 'at the same time' then use a ESP32 and the freeRTOS OS.

global variables are initialized to zero by default.

doubt an OS is going to make things happen faster

what is same time? within 1sec, 1msec, 1usec, 1nsec, ...

An ESP32 boots into freeRTOS. On an ESP32 freeRTOS is always running. Everything else added, like the ESP32 Arduino Core loads on top of freeRTOS, slows things down.

With an ESP32 and using multi core capabilities of the OS 2 tasks can be actually be running at the same time. And if one was to use the other processor, ULP, one could be running 3 things at the same time.

If you want to know more about the ESP32 or freeRTOS clicky clicky.