How do I get my same email to open in my new Iphone 17

There are at least two factors here. - There is no version of Thunderbird that runs on iOS, so you will need to find another email app that can do IMAP and SMTP mail, which are the standard Internet email protocols. I don't use Apple products, so I can't recommend one, but I know they're out there. When you find one, set it up to use IMAP, ''not' 'POP3. - The email program on your PC (Thunderbird, I presume) should also be set up as an IMAP account, ''not'' POP3. If all devices that talk to your email server are using IMAP, they will all synchronize with each other and all will show the same emails. If any one of them is using POP3, they will likely get out of sync and create confusion. The article below discusses IMAP and how it is an advantage in a situation like yours: https://support.mozilla.org/en-US/kb/imap-synchronization