You can acquire that debt across the direct property and / or the DST/TIC.  

The ability to use leverage to acquire more attractive assets and amplify their potential gains4.

However, co-living allows you to acquire properties with as little as 0%-5% down, drastically reducing the amount of cash required.Instead of needing $100K+ to buy a rental, a co-living strategy lets you start with a fraction of the cost while achieving higher returns.3.

I am researching my first deal in town (a foreclosure), and hoping to slowly but surely acquire properties for cash flow and retirement security. 

What if franchising is part of the strategy, with a long-term goal of acquiring properties as well?

There is no specific IRS-mandated minimum holding period for a property acquired through a 1031 exchange before you can retitle it, that's why it's hard to find an answer. 

Acquiring pre-existing rental portfolios?

If you take out debt to acquire, you will be negatively leveraged.  

Over the last several years I've been in a heavy cycle of acquiring and building rental portfolio, flipping, contracting, and being a realtor.

While the initial years might not be financially lucrative, the knowledge and skills you acquire will be invaluable.