ARM Exception Levels remain same for all ARM architectures?

No, different Arm architectures (Cortex-A/R/M) may have different Exceptions Levels.  You can google search Arm Architecture Reference Manual for the details.

  - https://developer.arm.com/documentation/ddi0487/ga 

If you just want to have a quick result, 

• For Armv8-A/v9-A aarch64, you can refer to https://developer.arm.com/documentation/102412/0102/Privilege-and-Exception-levels 

No, different Arm architectures (Cortex-A/R/M) may have different Exceptions Levels.  You can google search Arm Architecture Reference Manual for the details.

  - https://developer.arm.com/documentation/ddi0487/ga 

If you just want to have a quick result, 

• For Armv8-A/v9-A aarch64, you can refer to https://developer.arm.com/documentation/102412/0102/Privilege-and-Exception-levels