This really depends on how limiting you want to be. In general, though, Protestants don’t agree on anything. Even on the two major Protestant doctrines, Sola Scriptura and Sola Fide, different groups have different understandings of them.
On Sola Scriptura, more traditional Protestants may see it as simply stating that Scripture is alone infallible but still respecting and using tradition, but more Evangelical Protestants often take it to mean that Scripture should be the only reference point for doctrine and that skepticism is the only appropriate response to tradition. Many Pentecostal groups throw a further wrench into things by permitting things akin to private revelation in Catholicism.
On Sola Fide, more traditional Protestants tend to see it as including an element of commitment as part of the faith. Many modern Protestants, though, find this commitment to be an addition onto faith, making it contrary to the Sola Fide teaching.
You also can’t get down to a consistent view of God. The Trinity is up for debate. Whether or not God loves everyone is up for debate. Whether or not God is omniscient is up for debate. Whether or not Jesus is God is up for debate.
And then there’s no consistency on morals and spirituality. There’s not even a consistency in how to approach them, with some being incredibly rigid on what is/isn’t allowed while others are considerably more open to different personal moral codes and spiritual practices.
Of course, there’s also no consistency on what is a sacrament, whether there are sacraments, what sacraments do, what the Bible is, in what ways Scripture is reliable, etc. Basically, there’s no consistency.
With all that said, some Protestants do seek to limit the definition of what it means to be Protestant, but of course Protestants can’t agree on who is and isn’t Protestant.
