You will not always have a coordinated 5-stack. When playing with randoms without microphones, you have to adapt your playstyle to use them to your advantage. The most vital solo-queue skill is the Trade Kill.
What is a Trade Kill? If your teammate pushes a corner and dies to an enemy, you must immediately swing the same corner and kill that enemy. The enemy's crosshair will be displaced, their recoil will be active, and they will likely be low on health.
Monitor your raw fragging output and survivability over time to ensure you are consistently winning your 1v1s.
Are you carrying your weight? Check your exact ADR to see how much raw damage you inflict per round.
The Golden Rule of Spacing: To trade effectively, you must understand spacing.
If you follow too closely, one enemy spray will kill both of you.
If you follow too far behind, the enemy will kill your teammate and have time to reset their aim before you arrive.
The Sweet Spot: Follow your random teammate about 1.5 seconds behind. Let them take the initial risk, then swing instantly when they make contact.
See how often you successfully trade a teammate's death within the critical 3-second window.