In general, the pilots are required to have good visibility to execute any maneuvers during normal operation of the aircraft. According to Federal Aviation Regulations Part 225, Section 773- Pilot Compartment View, during non-precipitation conditions,
Each pilot compartment must be arranged to give the pilots a sufficiently extensive, clear, and undistorted view, to enable them to safely perform any maneuvers within the operating limitations of the airplane, including taxiing takeoff, approach, and landing
The FAA advisory Circular 25.773-1 Pilot Compartment View design considerations gives certain guidelines for ensuring pilot visibility.
Pilot compartment view from FAA AC 25.773-1 Pilot Compartment View design considerations
The figure shows a pilot compartment view for optimum collision avoidance
when seated in the left (port) seat. For the starboard side, all left/right dimensions are reversed.
Usually, the aircrafts offer better visibility compared to the guidelines. For example, the A330's visibility (from Flight deck and system's briefing) is given here.
Image from A 330 Flight deck and system's briefing
The actual visibility of the pilots will vary according to the seat position For example, the following figure shows the variation in pilot visibility in Boeing 727 when seat position is adjusted.
Image from Airplane Design- Layout Design of Cockpit, Fuselage, Wing and Empennage by Jan Roskam
Of course, the pilots can see things which is normally not visible though the windows through cameras mounted on the outside, like on top of vertical tail in A380.