If I speedrun minecraft 1.16+ then what's the minimum time to submit my run? Is it like 20minutes and under?

Please see this: https://www.speedrun.com/speedrunning/thread/6tgel

Edit: You can submit any time.

First, read the sticky thread in this forum about specific game-related questions.

Second (since it's not really related to Minecraft), there is no "minimum/maximum" time for submitting your speedruns. You speedrun something, and you can submit it, whatever time it takes.

Game moderators might or might not reject your run if you are clearly not making an effort to be fast. For extreme example, submitting 1-hour casual gameplay when speedruns are typically 5 minutes or less. But other than that, "slow" speedruns should be accepted.