This depends on your individual task and the condition of your website. Give us as precise a description of your website as possible and provide us with your complete access data.

For example, we can usually complete the following work within half an hour to an hour:

minor adjustments to the design (fonts, colors, text sizes etc.)
Installation and setup of plugins
Creation of a child theme
Optimization of individual images
Setting up Caching & Minify
Creating and scheduling backups
Installation of updates for WordPress, plugins and themes
Setup of webmaster tools
Fixing bugs in plugins or themes

If you want to be absolutely sure, please ask us for a cost estimate before processing or set us a limit for the effort.