Depends on which texts you are interested in? Texts from WordPress itself can be suggested for customization here: https://translate.www.ads-software.com/locale/cs/
Plugins have their own directories where you can suggest text changes. It depends on which plugin you are using. For purchased plugins, you would have to contact their developer. The same applies to themes.
It would also be possible for you to adapt the texts in your installation yourself. The Loco Translate plugin can help with this, allowing you to adapt the text files of WordPress, plugins and themes. However, make sure that you do not adapt the supplied files but a copy of them. Loco Translate and WordPress will then ensure that these copies are used.
