The MAX32666 contains a BLE5 module, and has a maximum transmitting power of 4.5dBm in higher power mode which will translate to different effective ranges depending on the transmitting frequency and the environment. At 125kbps the effective range could be up to 50m in good conditions, in enclosed conditions it's likely to be closer to 20m. At high frequency mode the range is significantly reduced (<10m) but the signal will be less susceptible to noise and environment conditions.
The gain of the receiver and transmitter antennae also play an important factor in determining the range. The MAX32666Fthr antenna has a max gain of 1.5dBi which will extend the range at high frequencies.