You don't know that. There are already plenty of examples of countries that have had hard lockdowns, no lockdowns and medium lockdowns, and the results are really inconclusive. The only pattern I can see is that the number of the infections is following the weather and the season, like flu viruses always do.

"huge" numbers of people are not dead, look at excessive mortality, adjusted for population, compare 15 years back. Lo and behold we have had several deadlier years.

In Germany all restrictions were lifted for six months and nothing happened, then suddenly infections went up when the weather got cold and OMG it's because we let people go out. Then we lift the restrictions slightly and now when infections go up again, following the next spell of cold weather, we are certain that it was because we let some people go to the hair dresser.