I want to install macOS 11.0 or above in sierra 10.13.6

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.

Does this computer appear as Listed and qualifying for an upGrade to a newer version of macOS? 

The below link will help identify which version of macOS  this computer may Qualify to run.

I do not see anything listed from 2012 to qualify for running macOS 11 Big Sur

macOS Big Sur 11 hardware requirements

• Oldest MacBook Pro MacBook Pro (Retina, 13-inch, Late 2013)
• Oldest MacBook Air MacBook Air (11-inch, Mid 2013)
• Oldest MacBook MacBook (Retina, 12-inch, Early 2015)
• Oldest iMac Pro (2017)
• Oldest iMac (21.5-inch, Mid 2014)
• Oldest Mac mini (Late 2014)
• Oldest Mac Pro (Late 2013)

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

You need a 2012 or later Mac to do so.