A new CSS campaign, as every new campaign on Google Ads, will experience a learning period during which the campaign will not perform at its best. Therefore you might consider using a lower budget during this initial phase and adjust it after the learning period has ended (up to 15 days from the start of the campaign).
When it comes to campaign creation, you can decide to set up a Standard or Smart Shopping and benefit from the CPC drop. There are many strategies you can use when creating a new Comlyn CSS campaign, here follows some of them:
Your existing Shopping campaign is already performing well
Create a parallel campaign, so you can do double bidding (show more products for the same search query), getting more clicks at a lower CPC, and at the same time being able to compare the performances of the campaigns and adjust the budgets.
Your existing Shopping campaign is not performing well
Consider pausing the campaign and creating a Comlyn CSS campaign. A CSS campaign allows you to be more competitive by entering every auction with the full bid. You do not have to pay any margin beforehand as it is the case with Google Shopping CSS.
Combining standard and smart shopping campaign
You can create a Standard CSS and a Smart CSS Shopping campaign in the same account, in order to benefit from the advantages given by both of them and at the same time benefiting from the CPC discount. However, bear in mind that if they both advertise the same products, the Smart Shopping campaign has priority over the Standard Shopping campaign. Therefore you might consider setting up those campaigns with different products.