We can’t send anyone to Hell so it would be an empty threat.
But we can say what the Bible says about it. I didn’t write the Bible so don’t blame me.
For me it is a matter of how Christ would want us to present the gospel, which He commanded us to do before He ascended into heaven. The goal ought to be converting as many people to a belief in Christ as Savior, rather than condemning them to hell for failing to believe. Offering the hope of salvation is much more likely to result in that salvation than is, as too many do, threatening the condemnation of hell. True, they are, in a way, two sides of the same coin, but I see and read about so many people who seem almost to enjoy telling non-believers about hell and leaving the good news of Christ nearly ignored. I think that is pretty close to the crowd who was about to stone the woman caught in adultery before Jesus addressed them.
We should find the most effective means of presenting the gospel with the goal of as many people as possible, never forgetting that faith is not something we can choose, but it is the gift of God. Ephesians 2:8.