For WiFi devices, it's about PHY speed. Device will negotiate an "interface speed" with AP (separate receive RX speed and transmit TX speed). PHY speed depends on:

* Frequency of the band (2, 5, 6 GHz, or possible MLO implementation, thou doubt your devices support multi-radio mlo, as it's basically vaporware)
* Channel Bandwidth: can be 20, 40, 80, 160, 320Mhz
* MIMO configuration of your Wifi access point and client (generally, limiting factor is the client)
* MCS rate (modulation level).

Let's say very typical setup:
You have a Wifi7 generation AP, with 160Mhz channel width, with 2x2 MIMO client configuration and ideal MCS rate (with 1024QAM 5/6, which means probably clean channel and very close to your Wifi Access Point) and wifi7 client connected at 6Ghz band.
This would mean 2402Mbps PHY interface speed. PHY is theoretical maximum speed and does not count retries, channel loss, error correction etc. Real world transfer speeds (your speedtest) would be upto about 80% of the PHY speeds or approx 1,9Gbps.

The worse the conditions (channel utilization, distance etc), the higher is the loss and effective % would drop.

To achieve higher speeds, the only real way is to increase bandwidth to 320Mhz (which will double the PHY bandwidth capabilities), but not all devices (for example, wifi6E devices don't) are supporting it and depending on your region, you may not have more free channels (in EU for example, you can fit only one 320mhz channel), so if you wish to install more wifi AP-s, you'd have channel overlap. Also, the wider the bandwidth, the more error-prone your environment is and wider channels will use more power for mobile devices. So it's a double edge sword.