I am not entirely clear where you are attempting to upload for OTA.

If you put the IP address of you board into into the serial port field and press ENTER then the Visual Micro upload should use OTA. IF you then switch on the compile verbose and upload verbose options on the vMicro toolbar you will see what is used for the OTA upload.

If you then see an error please post it here but in any event please post the info requested in the yellow box near the top of this page when creating forum threads. Most boards have different options so our advice can only really be given when the know what you are using and which tool chains you have installed.

if you switch on the verbose upload and then add any ip address as outlined previously you will see the command that we use to upload for ota. The command pattern is read from the esp32 toolchain platform.txt. The instructions in the yellow box near the top of this page also show how to switch on the "show build properties" option. That combined with verbose show all the patterns we have discovered and the final command to upload for ota

This is the verbose upload I see when I set a random IP address for a test. You will see that Visual Micro calls the espota.exe that is supplied with the toolchain. It might well be doing some extra stuff but you can use the .exe too.

Uploading 'Sketch38' to 'ESP32 Dev Module' using '192.168.8.122'
Uploader started for board ESP32 Dev Module
Upload method will be: bootloader
Uploading via Bootloader
Port Properties (network)
C:\Users\[your xe -i "192.168.8.122" -p "3232" "--auth=" -f "C:\Users\[your name]\AppData\Local\Temp\VMBuilds\Sketch38\ESP32_~1\Release/Sketch38.ino.bin"