I would like to connect my iPhone Roku account to a V1Z10 tv
Is V1Z10 a model number? Or do you mean VIZIO? I just did some quick searching and couldn’t find that model number and also I didn’t have any luck finding Vizio Roku TVs. If it is a Roku TV, it should offer to link to your existing account when you set it up. If it is a used TV, that wants to connect to someone else's Roku account, then you may need to factory reset it.
If the (presumably Vizio) TV is not a Roku TV, then there is nothing the Roku app on a phone can do with it directly.
If you install a Roku streaming device on the TV, then the Roku app on a phone can connect to the Roku and control that, which you then view on the TV.