Hi, I use adobe sketch very first time and I found some tools are missing. I haven't got pencil icon on the top bar and colour palette on the side. Also I can't see brush size slider either. How can I found them?
It looks like you're on an iPad Pro? If so, the reason you don't see the pencil icon in the top nav is because the only stylus supported in the iPad Pro versions of Adobe Sketch and Adobe Draw is Apple Pencil.
Tap any of the brushes in the toolset to open the Color menu (and the brush slider).