I would like to know how to protect color with brush tool ? if this manipulation is possible (like paint tool). Thanks.
I’m not sure if I understand the question well, but when you protect a colour, by right-clicking on its swatch and selecting “protect colour”, you will not be able to fill or repaint an area or line filled/drawn with it.
A different thing is when you trace over a brush line with another line: you’re not actually painting but tracing over it. In this case, if you want to preserve the original line, you can draw behind it by choosing that option on tool properties.