The Age of this computer will Govern what newer version of macOS it will Qualify to install. Use About this Mac from the Apple Icon on Desktop - the required Information will be there.
With the above information in-hand - follow this How to get old versions of macOS and verify what version this computer Qualifies to install. For Best results use Safari to commence the download as Others may not work.
Safari will open a redirect and open the Apple Store where the download can commence.
Technically possible to jump from macOS 10.13 High Sierra released in 2017 to Monterey macOS 12 released in 2021.
But your may consider moving up is steps.
So many things in macOS have changed since the era of High Sierra including possible EFI Boot ROMs that need to Flash the Computer ( not the Drive ) .
Which brings the point that in Monterey -The EFI Boot ROM expects to be installed on an Apple Original Drive and not onto an After Market Drive
Should this computer have an After Market Drive - caution as the Monterey EFI Boot ROM may Refuses to install and refuse to install Monterey
The work around would to put the Apple Original in the computer and Install Monterey
The reverse the above step and install Monterey to the After Market Drive
Does this computer appear as Listed and qualifying for an upGrade to a newer version of macOS?
The below links will help identify which version of macOS this computer may Qualify to run.
Computer Qualify for the Monterey upgrade
macOS Big Sur 11 hardware requirements
macOS Catalina 10.15 hardware requirements
macOS Mojave 10.14 hardware requirements
Make Time Machine Backup is very useful
Notation - Mojave is the Last version to support 32 bit applications / extensions and Drivers. Catalina, Big Sur, Monterey, Ventura supports only 64 bit and there is no workaround.
Suggest using Go64 to find 32 bit application before attempting the upGrade. Some or many of the Application already installed may require an update or upGrades to 64 Bit Version
