I had to look up what Polar Tracking is. No, LibreCAD doesn't have this feature, at least not completely.
With the 2Points line command when specifying the second point, you can restrict the angle to 15° steps by pressing the shift key and then use snap or choose a point somewhere. But sadly you cannot simply enter a length. This is a feature that is often asked for. Maybe developer dxli, who presently is adding and fixing all sorts of things, can be lured to this.