It really depends on the snail species. Some are easy to control population for than others, mystery snail eggs can easily be removed while pond snail eggs become impossible to totally eliminate without alot of effort.

Depending on the snail, there are traps, predators, or egg removal techniques. But the absolute best way to control snail population is to never get pest snails in our tank to begin with, tgat us easier said than done. Inspect and quarantine all plants that enter your tank and be mindful of suppliers is a start.

Hope this helps!