What PG600 said.
Sweet spot for 028 0r 026/260 is 16" bar 0.325 " pitch 0.063 gauge. They will pull a longer bar but are marginal for power in a full cut/hardwoods, you'll have to go easy and not file rakers too deep. Also makes a difference with 7- vs 8- pin drive sprocket. A 7- will be slower but handle bigger cuts better without bogging.
If you are cutting dirty wood, or turf the blade in the ground get a semi-chisel chain that stays sharp better, if not full chisel cuts faster. For stihl chain that would be 23 RM or 23 RS
If you don't have a lot of time using a saw start out with a "safety" chain to help reduce kickbacks. I don't like safety chains but I've been running saws since the 1970s