Is there a silver bullet to 'hack' your launch engagement?

Hello everyone! I believe the title makes it clear. Are there any strategies or channels that makers are using to scale their number of supporters for a product launch? I'm asking because I'm currently trying the following methods: 1/ Direct messaging my LinkedIn network individually, which isn't scalable, but so far has yielded a 25% conversion rate. 2/ Engaging here on Product Hunt, which is very efficient (almost 100% conversion), but it's not very effective in terms of volume. 3/ Participating in other communities: this is the easiest method, but it has a very low conversion rate (less than 5%) when sending a single message to many people.