Hi @ClemParpa,
Could you please share a bit more about your scenario?
Do you want to manage the value of the Visible property of a control using a Button control?
If you want to manage the value of the Visible property of a control using a Button control, please take a try with the following workaround:
I add a Button control and a Label control within my PowerApps app's screen. The OnSelect property of the Button control set to following formula:
UpdateContext({LabelValue:!LabelValue})
The Visible property of the Label control set to following formula:
LabelValue
The Text property of the Label control set to following formula:
"Flow Test"
For managing the value of Toggle control, the OnSelect property of the Button control set to following formula:
UpdateContext({ToggleValue:!ToggleValue})
The Default property of the Toggle control set to following formula:
ToggleValue

More details about UpdateContext function, please check the following article:
UpdateContext function
Best regards,
Kris