In 2025 does it make sense to build a 4plex and house hack it or is it better to buy existing multi-family? 

Multi-family properties many times provide a better return per square foot than single family, which would be to your advantage as well.As long as you're mindful of the reinvestment requirements and purchase at least as much as you sold and use all of the proceeds, you shouldn't have any issues with this strategy.

Quote from @Joseph Gary: Searching for a Multi-Family.

To determine price range, the first step is always figuring our how much you are pre-approved for; and that can vary significantly when you are looking at multi-unit properties because of the additional variable of rental income that can be included in qualifying.

If you want to learn about multi family, then connect with a multifamily investor.

Have you bought commercial multi out-of-state before?

We go above and beyond when it comes to protection.. starting with insurance coverage, sings in the listing and in the property that there is no guard on duty (as silly as that sounds), putting extra locking device high enough so youngsters can't reach, an alarm/beep system to alert them that door opens for those with small children (or elderly) so they cannot wander out in the backyard with no one noticing and risk drowning.

They seem to have a great system and I know they spend years before deciding on where to build there projects.

If you are going to self manage you will need to build business systems and get a list of reliable vendors.  

Many of my customers who are traveling nurses buy condos or townhomes in Florida as vacation homes, then rent them out when they're not in town.This system has proven to be very lucrative, as it allows them to service the mortgage debt and generate a good cash flow.