Android's built-in Accessibility really focuses on reading/speaking items on the screen and using gestures to move around.
For voice control, one possibility is Google's Voice Access app in the Play Store, and the intro tutorial does give a good example of the app's features, but there seems to be some problems with the form-filling (speech to text into a ...
Hate that when it happens.
My fix: Press Google assistant button on phone, button below volume up/down button on lgv40 phone on left side, starts Google assistant.
State "Open Settings"
Double press on general, then "Accessibility" then "Hearing" then turn off "Takback"