From Wikipedia: A design sprint is a time-constrained, five-phase process that uses design thinking with the aim of reducing the risk when bringing a new product, service or a feature to the market. The process aims to help teams to clearly define goals, validating assumptions and deciding on a product roadmap before starting development. It seeks to address strategic issues using interdisciplinary, rapid prototyping, and usability testing. This design process is similar to Sprints in an Agile development cycle.
Check:
https://en.wikipedia.org/wiki/Design_sprint
https://designsprint.org/de/
technique