How can I use a button name to change a boolean value in the script?

bool.Parse, Convert.ToBoolean convert string to boolean value, which means e.g. "True" of type string to true of type bool.

Your button names aren't "True" and "False", so they can't be converted to boolean.

What you are trying to do is not called "converting to boolean". You are trying to find a variable by a string name. This is formally doable via reflection, but reflection comes at a cost of performance and should not be used casually.

The solution to your problem is storing your variables in a Dictionary:

Dictionary<string, bool> _flags = new() 
{
    { "EVM", false },
    { "small", false }
    ...
};

Then, in your SizeClicked yo can do:

public void SizeClicked()
{
    var btnName = EventSystem.current.currentSelectedGameObject.name;
    _flags[btnName] = !_flags[btnName];
    ...

_flags[btnName] is how you access values stored in a dictionary by key.

• _flags[btnName] = true; is how you set the value.
• var value = _flags[btnName]; is how you get the value.
• if (_flags[btnName]) { } is how you check the boolean value.

There is also a solution without dictionary. Either use if:

public void SizeClicked()
{
    var btnName = EventSystem.current.currentSelectedGameObject.name;
    if (btnName == "EVM");
        EVM = !EVM
    else if (btnName == "small")
        small = !small
    ...

or switch:

public void SizeClicked()
{
    var btnName = EventSystem.current.currentSelectedGameObject.name;
    switch (btnName)
    {
        case "EVM":
             EVM = !EVM
            break;
        case "small":
            small = !small
            break;
        ...

Unfortunately, I didn't get to see your photos!

For button names, I think you should put a name that is understandable and related to the button, and put a 1 or 0 at the beginning or end of their name. My own suggestion is that the first name is the buttons, so I will give an example with the same method.

bool isZero = myButtun.name.StartsWith(0);

I don't know why you want to take a pulse from a button that has been saved correctly and vice versa.

I wish you could explain more about what you want to do so that we can achieve a better result.