Hello @Laurenbiostarus ,
To show multiple shipping options at checkout on Shopify: Go to Settings > Shipping and delivery, select a profile, add rates, and pick shipping methods to be available at checkout under SERVICES.
Please ensure that you have added weight for your product.
Also, ensure that you have configured the correct ship-from locations.
Finally, check whether the from and recipient addresses are serviceable for the carrier.
If the issue persists, you may contact Shopify Support.
If you have your own account with USPS, UPS, FedEx, or DHL, you can try the PH Multi-Carrier Shipping Label app to integrate and show carrier-calculated rates at checkout.