Here are all the controls for Call of Duty Black Ops 4 on the PC.
Primary Controls
Fire – Left Mouse Button
Hold Aim Down The Sight – Right Mouse Button
Reload – R
Switch Weapon – Mouse Wheel
Melee – V
Special Ability – Q
Interact/Use – F
Throw Frag/Use Equipment – G
Tactical Equipment – E
Health Kit – X
Steady Aim – Left Shift
Boost – Left Shift
Show Scores – TAB
Change to Class 1 – Num1
Change to Class 2 – Num2
Change to Class 3 – Num3
Change to Class 4 – Num4
Change to Class 5 – Num5
Change to Class 6 – Num6
Movement
Forward – W
Move Back – S
Move Right – A
Move Left – D
Fly Up/Stand/Jump – Space
Prone – Ctrl
Change Stance/Slide – C
Sprint/Hold Breath – Shift
Turn Left – Left Arrow
Turn Right – Right Arrow
Look Up – Up Arrow
Look Down – Down Arrow
Hold Mouse Look – Caps Lock
Other Controls
Voice Chat (Push to Talk) – B
Screenshot – Print
Open Friends Menu – F1
Open Social menu – F2 or O
Open Settings Menu – F3
Open Store – F4
Accept Party Invite – F7
Dismiss Party Invite – F8