Size of vectors in SVE2

Hello,

I want to use the SVE2 instruction set. To this end, I have created a VM in a known cloud provider based on armv9 architecture which supports SVE2 instruction set.

I want to ask the following:

1) How can I determine the size of the vectors? The only way that I am aware of is by executing the following asm code:

rdvl            x9, #1
cmp             x9, #16
bgt             .label1

And branch based on the VL number. Is there any other command in the operating system level?

2) How can I change the size of the vectors? Currently, I can see that the size in my VM is 128 bits (using the aforementioned asm code). Is there a way to increase this value (provided that the underlying processor supports it)? For example, a command in the operating system level?

3) I want to have vectors whose size is bigger than 128 bits. Is a processor that supports this enough or do I need anything else (for example a specific version of a specific operating system, specific gcc, and so on)?

4) Do you know a cloud provider which supports armv9 VMs with vector size bigger than 128 bits?

Thank you in advance,

Akis