Hi, my iPad doesn't update it has iOS 10 and I can't find the way to update the system

It depends on hardware compatibility.

If your model says that it is up to date, it means that your iPad model cannot support more recent iOS versions than the one that's currently running on it, due to hardware incompatibility.

Regards

Giulio

If your iPad has been stuck on iOS 10.3.3 for the past few years, with no major upgrades/updates forthcoming, then you own a 2012, iPad 4th generation.

A 4th gen iPad cannot be upgraded beyond iOS 10.3.3/10.3.4 for WiFi & cellular data models.

A 4th gen iPad is a NEARLY 8-year old device, now!

These older iPad models are too old, now, too underpowered and completely incompatible with any of the current and future versions of iOS/iPadOS.

These old 8 and 9-year old iPad models will be completely OBSOLETE by the end of 2020!

Sorry, but it is what it is, today, in the year 2020!

Here's why and what you will need to do about it in 2020!

Tap and read my link below for my additional info about your old iPad model.

If you own OLD 8 and 9 Year Old iPad mo… - Apple Community

Sorry & Best of Luck to You!

If your iPad has been stuck on iOS 10 all these years, you have a 4th generation iPad, which is too old, too under powered, no longer supported and completely not capable of being updated further. If as I suspect you need the newer iOS level on your iPad for many many apps, then you need to invest in a newer iPad capable of running the now required 64 bit software.

Sorry, it's time to retire your old device.