change values in the required radial.json file and get the required icon colours and size:

{

"name": "Viewport settings",

"command": "viewport:settings",

"items": [

{

"command": "viewport:toggle-orthographic",

"size": "25",

"fill": "red",

"icon": "orthographic-view",

"label": "Toggle orthographic"

},

{

"command": "viewport:toggle-x-ray",

"icon": "xray",

"label": "Toggle X-ray"

},

{

"command": "viewport:toggle-overlays",

"size": "25",

"fill": "green",

"icon": "overlays",

"label": "Toggle overlays"

},

{

"command": "viewport:toggle-render-mode",

"icon": "render-mode",

"label": "Toggle render mode"

},

{

"command": "viewport:toggle-edges",

"size": "25",

"fill": "blue",

"icon": "edge",

"label": "Toggle edges"

},

{

"command": "viewport:toggle-faces",

"icon": "face",

"label": "Toggle faces"

}

]

}