Whats the best sell order type for me to use?

I own some stock that I’ve held for years and plan to sell in coming months. I want to get ahead and set up sell orders today, if the price is reached in coming months…

For example I hold some Palantir. I want to sell it at $120-$125 range.

Would I simply set a sell limit order of $120?

I hardly ever sell so want to get this right haha.

I recaLl there being a demo environment where I have fake money. How can I access this to try and simulate selling situation via the mobile app?