Hello there Sherri Henderson. We have read your message We try to help you.

You are having a new iPhone 12? You like to install Thunderbird .exe for mobile devices? To use Thunderbird on that new phone.

There is no Thunderbird mobile for iPhone. Also on the iPad there is no installation for this.

You can install Thunderbird on the Mac device. https://support.mozilla.org/en-US/kb/installing-thunderbird-on-mac

You can download other email programs for your iPhone.

There is Apple- mail for you in the App Store.

https://youtu.be/MVy3tG0kQV4 (Scanned with virus total)

Greetings Firefox volunteer.

Hello there Sherri Henderson. We have read your message We try to help you.

You are having a new iPhone 12? You like to install Thunderbird .exe for mobile devices? To use Thunderbird on that new phone.

There is no Thunderbird mobile for iPhone. Also on the iPad there is no installation for this.

You can install Thunderbird on the Mac device. https://support.mozilla.org/en-US/kb/installing-thunderbird-on-mac

You can download other email programs for your iPhone.

There is Apple- mail for you in the App Store.

Greetings Firefox volunteer.

Short answer is the Thunderbird email client is only available for desktop as in Windows, Linux and macOS.

https://www.thunderbird.net/thunderbird/91.8.1/system-requirements/

There is no mobile version of Thunderbird whether for Android or iOS. Also the iOS version of Firefox is essentially a shell due to Apple's restrictions on things like what browser engine can be used and such so the Thunderbird email client would likely be in a similar situation if there was ever a version for iPhone/iPad.