Help New Campaign

I am an DM who wants to start a new campaign and I would like to ask for advice.

I have 2 - 3 years of experience as a dm and till this point only run self made campaign.

The campaign should be an large one (level 1 - 20) and one with with an huge open world to explore I have nothing against a campaign that could last more than a year (we play every two weeks).

Our play style is very flexible from an intense serious one to a goofy fun part.

Thank for the help reddit