How To Batch-Optimise Images For My Website

I thought that this query might already be answered on Stack Exchange, but I cannot find anything that quite has the nuance that I'm looking for.

I have a web server (through CPanel) for hosting my website, and a lot of images hosted there for a lot of my different blogs, projects etc. I also have a local version of these files on my PC.

I have found that a lot of my images may need optimising. While server space is certainly an issue, the most important thing that I am looking to solve is client responsiveness (i.e. browser loading times for visitors, both on mobile and desktop).

My questions are these:

• Is there a way to batch-resize images locally on my PC?
• What other image optimization should I be undertaking, and is there a way to do this in a batch as well?

I am happy to learn how to use command-line utilities, but a GUI solution would be even better.

Thanks so much for your help.