Michael Tichy and Rawen's models are fairly simple, but small scale.
They are also nicely detailed for their size.
I don't know exactly where to look for them.
I found this site that has some military models by them:
https://prmodels.webnode.cz/products...-michal-tichy/
I have a Leopard model by Tichy...not sure if it is in the above collection.
Tanks is not a subject that lends itself to really simple designs,
unless they are overly simplified, and then they're disappointing.
World of paper tanks has a good collection of models but they are not easy.
In fact, I found them quite challenging in many ways.
And I wouldn't suggest them to a real novice.
As for a free but really awesome model, paper-replika has some great Tanks.
Julius' Challenger is awesome.