Of course you can, BUT… it depends on the extent of the differences among the formats. UP sachets/stick-packs machines are designed to work with different formats. Thus you can definitely adjust some parameters like dosing range and bag length by HMI without the need for replacing any mechanical part.
However, whenever there are significant differences in formats (bag width change, high dosing range) the changeover must be foreseen in the machine design and some mechanical parts may need to be changed. Some solutions are more flexible and recommended for these cases as they come with an adjustable sealing block or a modular layout that allows for easy and quick changeover. In case of stand-alone vertical packaging machines the parts that are usually concerned in the changeover can be found in the dosing and sealing groups. In case of complete lines, these parts are usually located in the connecting units, conveying systems and carton forming and closing groups.