tahoma in iphone

Aftermarket fonts for iOS can be used in text editing apps, not for changing the system fonts.

Tahoma is a Microsoft font, bundled with a number of their products, not to be transferred to other devices. This font is also available to buy, e.g. for individual use (desktop workstations). Commercial font licenses do not seem to mention mobile, other than inclusion in apps for developers.

Installing Microsoft 365 (Office) on iOS will include Tahoma, for use within this suite, not other apps.

The iFont app (or similar) can be used to install fonts from files. For legal reasons, these should probably be free/open fonts.

You should be able to install extra fonts using an app like AnyFont. But such fonts can only be used in apps that have a font menu, like Pages. You cannot change the user interface font on the iphone.