This post shows you How to increase the size of the buttons on a ToolStrip in C# Windows Forms Application.
First of all, you should change the AutoSize property of ToolStrip control to False, then change Height of your ToolStrip control.
For example:
toolStrip1.AutoSize = false;
toolStrip1.Height = 50;
Next, You need to change the AutoSize property of the ToolStripButton to False.
toolStripButton1.AutoSize = false;
toolStripButton1.Width = 50;
Finally, Change the ImageScalingSize property of your ToolStrip control.
toolStrip1.ImageScalingSize = new Size(40, 40);