I found this online. I can't verify since I don't own a 7300.

IC-7300 digital modes/FT8 setup
WSJT-X Radio tab

Serial Port: /dev/cu.SLAB_USBtoUART
Baud Rate: 115200
Data Bits: Eight
Stop Bits: Two
Handshake: None
Force Control Lines: (Leave both empty)
PTT Method: CAT
Mode: Data/PKT
Split operation: Rig

WSJT-X Audio tab

Input/Output set to the 7300's USB device

WSJT-X Waterfall + Main Window

Bins/Pixel: 4
Start: 200-300 Hz
N Avg: 2
Palette: Digipan or to taste
Cumulative
Flatten: unchecked
Ref Spec: unchecked
Spec 30%
Sliders on default/center except upper-right adjust to taste, usually ~30%
Pwr slider 100%

7300 rig settings

Mode: USB-D
Filter Bandwidth set to widest possible (3.6k), sharp falloff
Function menu: AGC, NR, NB, Notch, Preamps, Vox, etc all turned off
Display typically set to waterfall + Meter
Set -> Connectors:
ACC/USB Output Select: AF
ACC/USB AF Output Level: 10-30% (adjust as needed for band, noise level)
ACC/USB AF SQL: Off (Open)
ACC/USB AF Beep: Off
ACC/USB IF Output Level: 50%
ACC Mod Level: 50%
USB Mod Level: 40%
Data Off Mod: MIC,ACC
Data Mod: USB
CI-V:
CI-V Baud Rate: Auto
CI-V Address: 94h
CI-V Transceive: ON
CI-V USB->Remote Transceive Address: 00h
CV-V Output (for ANT): Off
CI-V Baud Port: Unlink from [REMOTE]
CI-V USB Baud Rate: 115200
CI-V USB Echo Back: On
USB Serial Function: CI-V
RTTY Decode Baud Rate: 19200
USB Send/Keying: All Off except Inhibit Timer

Mac OS Settings

Applications->Utilities->Audio Midi Setup->USB Audio Codec 1: Left/Right both set to approximately -9.0db, adjust as needed while monitoring ALC levels on the rig. ALC should be at about 1/2 to 3/4 while transmitting. Some experimentation and outside verification (Web SDRs?) needed to make sure you're not overdriving the audio.
Silicon Labs CP210x USB to UART Bridge VCP Drivers installed: https://www.silabs.com/products/development-tools/software/usb-to-uart-bridge-vcp-drivers