Here's the thing.
You may not want to learn this, but this is the reality and how it is, nevertheless.
So, here it goes, for what it is worth to you.
Almost 6 years ago, Apple finally and quietly, with NO fanfare, did away with all 16 GBs iOS devices.
With iOS/iPadOS system software getting larger and larger, 16 GBs iOS devices were being choked with having very little internal, free data storage space to do very little with.
Today, in 2020/2021, Apple 32 GBs devices are now becoming the “new” 16 GBs iOS devices.
A 16 GBs storage iPad starts out, after initial drive formatting, at approx. 14.5 GBs of free, internal storage.
After the installation of iPadOS, at approx. 6 GBs, leaves 8.5 GBs of of free, internal data storage space.
iOS/iPadOS needs a minimum of 2-4 GBs of constant remaining storage, AT ALL TIMES to insure/ensure nominal, acceptable operation of all iOS/iPadOS functionalities.
This leaves a 16 GBs iPad with ONLY a practical, usable storage space of between 4.5 and 6.5 GBs AND THAT IS IT!
This is virtually NO internal data storage to do much of anything with that 16 GBs iPad!
Back in 2014, the iOS system software was NOT as large a file size, as it is today!
So, Apple, in 2014, were still offering iOS devices in 16, 32, 64 and 128 GBs internal storage sizes.
This is reason why Apple quietly, silently did away with all 16 GBs iOS device back sometime in 2016.
A 32 GBs storage iPad starts out with approx 30 GBs.,after initial internal flash drive formatting.
Minus approx. 6 GBs for iOS/iPadOS leaves 24 GBs.
Minus 2-4 GBs, for iOS/iPadOS system operational reserve, leaves approx. between 20-22 GBs of actual, usable data storage space.
This is 3-4 times the usable internal storage space of a 16 GBs iOS device, but CAN get also, get quickly swallowed up with data in a short period of time, if the data is not properly managed.
A 64 GBs storage iPad starts out with approx. 60 GBs.,after initial internal flash drive formatting.
Minus approx. 6 GBs for iOS/iPadOS leaves 54 GBs.
Minus 2-4 GBs, for iOS/iPadOS system operational reserve, leaves approx. between 50-52 GBs of actual, usable data storage space, which is a more more reasonable, usable and manageable amount of internal data storage space,
etc..
No matter what you do to try and gain some free storage on that over 6-year old, 16 GBs iPad, those efforts will be futile.
That iPad storage model will still have very little free data storage space left to do much of anything today in 2021.
Sorry, but this is that reality for your iPad model.
Today in 2021 and with iPadOS being 6 GBs, and somewhat over in file size, a 16 GBs iPad is virtually useless, now.
Sorry.
So Yes,
You really need to seriously consider a new iPad model OR a much, MUCH “newer” and less expensive, used iPad models, from better known, trusted Apple product/device retailers/resellers, with, at least, 64 GBs of internal data storage, as an absolute minimum now.
Sorry & Best of Luck to You!