Easiest way is go in and out of Schengen zone every 90 days. You then need to stay 90 days in the other place before you come back. Some examples of places you can go include UK (England, Scotland, Wales), North Africa (Morocco, Algeria, Libya, Tunisia, Egypt), Balkans (Bosnia/Herzegovina, Serbia, Montenegro, Kosovo, Albania, Macedonia) and possibly Bulgaria or Romania (not sure if they count as outside Schengen still) plus Turkey. Belarus, Moldova and Ukraine are options too, but might be a bit risky at the moment because of the war. I would ask around some people who have spent a lot of time in these countries (i've only spent longer periods in UK and Turkey) to see if they have any recommendations.