There are several plugins that can help you create rivers and streams. Some popular options include the River Tool, which provides an easy way to generate rivers with realistic flow and foam, and the Waterflow plugin, which can create detailed water simulation for rivers, lakes and oceans.
You would need to check with the respective plugin developers to see if they are compatible with the latest engine version. Additionally, UE5 includes new water and rivers systems, such as the Niagara particle system and the Flow Map, that may be useful for creating your desired water effects.