Hi Robert. Typically, the way I’ve seen some of our own customers ship larger items at a lower cost is through negotiated discounted rates with their carriers. If you’re just starting out, you might not get the lowest rates, but it’s worth discussing with carriers like UPS, FedEx, and others to see if any discounts are available based on anticipated shipping volumes. There are also specialist carriers who focus on shipping larger/heavier items too, which may be an avenue worth considering.
Then with free shipping, some sellers opt to absorb some of that shipping cost with orders over a certain value, or just cover it entirely.
I hope this is helpful! Happy to discuss more if required.