If each Maven run on a project results in always downloading dependency jars even though they have already been downloaded and stored in your local .m2 repository which is by default located at USER_HOME/.m2 e.g., on my Windows 10 machine, mine is C:\Users\ransk\.m2, then you only have to instruct Maven to operate in an offline mode.
One way to do is to locate the main Maven install directory, this is referred to as the MAVEN_HOME, which contains the settings.xml file in the conf directory, e.g. E:\tools\apache-maven-3.3.9\conf\settings.xml.
The offline settings is off by default and it only has to be turned on by ensuring you have the entry below in the settings.xml file.
With this in place, Apache Maven will check to see if required dependencies are available locally before contacting any remote repositories.