Let me share two videos with you below,
The first is about the spline tool, which lets you create curved lines. The pencil should not be pressed during the drawing of the curve, but you should not lift it off from the screen. Please only press it when the control points are placed.
The second video is about the adjustment of the splines, this is where control points are important. These are the points that you can move freely and deform the spline with.
If you have a tight corner, please do not place dozens of points next to each other, just make the curves longer as in the video below and trim the unnecessary ends from the lines.