If the car console is giving you an option to put the password in then you can do the following.
On Lexus plus app click on the person at the bottom of the app then sign out top right. I’ll attach a pic.
Log back into the app with your email or phone number (if you’ve added your phone number) then when you get to the next screen there’s an option to reset password at bottom rather than putting your old one in and try to set a new one, see if it will accept with no capitals, for example blue@15about if you have to set a capital then try using just 1 if it will allow.
Once you’ve set up your new password log in on the car console with that new password (that’s why I asked if it’s giving you the option in the car).
If that does not work then the more drastic option which is the one I did at the Lexus Garage (well they did it for me)
On the Lexus plus app instead of signing out as above, there’s an option to delete account on the same page as sign out at the bottom of page, delete account and delete app.
In settings in car remove your profile completely so it’s back to how it would be as a new car.
Download the app and start again with new password as above or resetting password on the password page.
Then set up your profile on the car from new.
On the Lexus plus app in security I have require authentication 12 hours (max) and always keep me logged in, pic attached.