If you don’t want to create a local test WP environment, you could create a second WP site at your hosting place. Just put it in a subfolder of your main site, as in www.example.com/devsite . Develop code (themes/plugins/etc) on that site, and test it on that site. If you want live data, you can ‘clone’ your main site initially to the dev site. Lots of plugins allow you to do this (I like “WP Clone” from Automatic.)
Create/modify code with your local computer editor, then upload it to your test site at your hosting place for ‘almost-live’ testing. Once you have the theme/plugin the way you want, install it on your live site.
“Purists” might argue that it is best to have a local WP system for development. But the above way works OK too, without the hassle of maintaining a local WP development site.
I have personally used BlueHost/JustHost for many of my WP sites for many years. My sites are not high-volume/high-visitors, and letting someone else take care of the server back-end processes is an advantage, IMHO. I use the above process for developing my plugins.