In Odoo, you can exclude certain packaging from the website by setting the "Website Visible" field to "No" for those packagings. This can be done on the Packaging form under the Inventory module.
To offer bulk discounts for larger size packaging, you can create a pricing rule under the Sales module. To do this, go to the Sales > Configuration > Sales > Pricelists and click on "Create" to create a new pricelist. Then, go to the "Pricelist Items" tab and click on "Create" to add a new pricing rule. In the "Product" field, select the product for which you want to offer bulk discounts. Then, specify the conditions for the bulk discount in the "Apply On" and "Based On" fields. For example, if you want to offer a discount for customers who buy more than 100 meters of cable, you can set the "Apply On" field to "Product" and the "Based On" field to "Quantity" and specify the minimum quantity in the "Minimum Quantity" field. Finally, specify the discount in the "Discount" field and click on "Save" to apply the pricing rule.
It is up to you whether to use variations or packaging to offer bulk discounts. Using variations may be easier to set up if you already have variations for different cable types, but using packaging may be more intuitive for customers if the packaging is the way the product is commonly sold.
