That depends on the changes you’re attempting to make.
If you’re attempting to change the design, colors, or other theme options using the Customizer, you can save those changes as a draft, without publishing them right away. You can even schedule the changes to appear automatically at a future date and time.
This video goes into more detail:
But if you’re attempting to make changes to existing pages or posts that have already been published, those changes will be published as soon as you save your changes.
We typically recommend you use a staging server — which is basically a mirror copy of your site. Make your changes on the staging server, and then, when you’re happy with your changes, you can push those changes to your live site with a click.
Most of the Managed WordPress hosts we recommend include a staging server as part of your hosting plan (one of the many reasons we recommend using a Managed WordPress host).
But if your current host doesn’t offer staging servers, you might consider a third-party solution like WP Stagecoach.
Hope this helps!