You can do this by setting the property of the TextBox:
Multiline = True
To add multiple line in a text, for example, to show 2+2 = 4
TextBox1.Text= "2+2=" & VbcrLf & "4"
This will show output as:
2+2=
4
VbcrLf
breaks the line and let you write in the next line
solved How to control text box multiple lines in vb 2017