Hello @vpchamber,
Hope you are well and thanks for posting your question here.
You need to write some CSS code inorder to make the slider height smaller. Go to Customize-> Themes Options-> Advanced Options-> Custom CSS and paste the following code:

#main-slider {
max-height: 500px !important;
}
@media only screen and (max-width: 500px) {
#main-slider .cycle-caption {
    left: 13%;
    padding: 3px 6px;
    top: 150px;
    width: 62%;
}
}

When you are done, click save and publish. Now the slider height should be smaller. If you want smaller than this height then you can adjust it by changing the value from 500px to lower value.

Thanks.

Hello @vpchamber

Please try and add the following CSS code to Dashboard / Appearance / Customize / Theme Options / Advanced Options.

#featured-slider {
max-height: 500px !important;
}

And you can add image of any size the slider will crop the image to a perfect fit. But try and add image of height greater than 500 px and width greater than 1000 px though its not a compulsion.

Hope this will help to resolve you issue.
Let me know how it goes.

Best Regards!!!