Can I set the core voltage of the microcontroller by programming?

[KKIM.6]

I want to reduce the output voltage of the GPIO pin by programming. So, I'm finding a way to reduce core voltage.

Is it possible? then where can I do it?

If not, is the only way to change fixed LDO physically?

For example, using 2.0 V-output LDO.

[Tesla DeLorean · Accepted solution]

Use a level shifter IC, or an opamp or the DAC depending on expectations?​

[Tesla DeLorean]

Several of the L4+ and L5 have a VCCIO pin for Bank G

[KKIM.6]

My application is a bioimplant. So, It is not preferred to use many extra components.

Is there any other way?