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.