First recommendation: Leave it to the people getting paid to manage and improve it. If they need your help, they will ask for it.
If you really want to contribute, go to them directly and ask if you can help with anything. They'll appreciate your direct approach. Tell them you keep hearing complaints from people around the office regarding the WiFi usability and you wonder if you can do anything to help.
As for the actual technical answer to the technical problem of WiFi network capacity:
Each network differs according to its design and implementation. Most WiFi access points designed for business or enterprise use vary between 50 to 200 maximum connected devices so if you have an office of 100 people and assume they each have 2 to 3 devices, you need more than 1 access point for that office though how many you need depends on the model and manufacturer specifications.
Additionally, each access point will only carry so much traffic according to its design, features and connectivity. A 1 Gigabit uplink connection for the access point will never carry more than about 970 Megabit of actual throughput though depending on the radios in use, frequencies in use and other configuration specifics, the actual performance of all the traffic of the users on the access point may be much less. Some access points now have 2.5 Gigabit interfaces but that will require matching switch ports and appropriate cabling for them to perform at anywhere near that level.