It depends on how much we are talking about in absolute values. If it's a lot of money, I'd sell 50% and the rest I'd hodl to see if it rises any more.
Yes, partial sale can be a good solution in this situation. If the project has very good development prospects, then I would sell only a small part, and leave the rest in order to sell it in the future. But I met people who would sell all the coins of this project and invest in another project, which in their opinion can soon grow.
That's the only good decision to make. People that sell everything often regret it.