Square shaped button with icon in Mui [v6.1.3]

Use the sx prop to add css directly to the components. within sx: {{}}

1. Set equal padding with p: 1 or any other value
2. Set min-width to be 0 with minWidth: 0

So it comes out to be

<Button variant="outlined" color="text" sx={{ minWidth: 0, p: 1 }}>
   <NavigateNext />
</Button>