You should be aware that macOS 26 Tahoe is not appearing in the Apple Apps Store
Therefore it will be difficult to acquire the Full Version of Tahoe which is Required in-order r to make a Bootable Installer
Predicated on you Apple Computer Qualifies for Tahoe
You may be forested to use a specific Terminal command to manually download the Full Version ( about 17 GB )
Should you what to explore this manual option
Please do post a reply requesting your interest in this
Create a bootable installer for macOS
excerpt from above
Do you need a bootable installer?
You don't need a bootable installer to upgrade macOS or reinstall macOS. However, a bootable installer can be useful when those or other macOS installation methods are unsuccessful, or when you want to install macOS on multiple computers without downloading the installer each time.
Creating a bootable installer is not the same as preparing an external storage device for use as a startup disk.