Your very old iPad2 can only be updated to iOS 9.3.5 (WiFi Only models) or iOS 9.3.6 (WiFi & Cellular models).
Apple formally ended update support for iPad2 in September 2016. iPad2 cannot be updated to iOS 10 or later major versions of iOS, as the internal hardware does not meet the minimum technical requirements for new versions of iOS/iPadOS. This limitation cannot be bypassed - in addition to which, iPad2 is a 32-bit architecture device, whilst all recent versions of iOS/iPadOS are designed for 64-bit hardware platforms.
You may wish to consider that compatible Apps for your iPad are increasingly difficult to find - as third-party developers are increasingly dropping support for older versions of iOS preceding iOS11/12 (and some, for technical reasons, have dropped support for all versions of iOS prior to iOS/iPadOS 13). As older versions of Apps are removed from the Apple App Store, you’ll not be able to (re)download or install them.
As such, if you want or need to access most current Apps, requiring a higher version of iOS than you iPad can support (such as MS Teams), you’ll need to consider replacement of your iPad with a newer or current model.
Even the most basic current iPad7 will massively outperform you current iPad - and is compatible with the vast majority of current Apps.
I hope this information provides helpful clarity as to your available options - and the limitations of your current iPad2.