First, if your existing insurance is ACA compliant -- they are required to cover emergency services, even if you are outside of your network/region.
Are you traveling for such a length of time that you'll need regular/routine medical care, that can't be done via tele-medicine?
One option is to just pay cash/out-of-pocket for those planned routine expenses.
I guess, another option is to look into short term plans. Last time I was looking into them, I think UNH had a national network of doctors. Might be a good stop-gap for a short term plan ?
https://www.uhc.com/health-insurance-plans/short-term-health-insuranceIf, on the other hand, you are planning for international travel, then you could buy a supplemental policy for Global Medical Transport... I think the major insurance companies (Berkshire Hathaway, Travelers, etc.) offer policies for this.