Well there are some places that uses java so I kept my java 11.0.1 64bit installed.

Hi coriolano, Internet Explorer 11 can still run Java for sites that may require it. I don't know whether it will use 32-bit or 64-bit Java.

coriolano said

Good afternoon. I have installed on my PC the Firefox version 63.0 for 64 bit. So far I have used Java 32 bits, because Firefox does not accept Java 64bits. I know the new Firefox does not use any more plug-ins. Should I then delete Java from my PC? Thankful.

Firefox 63.0 does not allow the NPAPI Java Plugin to run whether 32-bit or 64-bit.

Why do Java, Silverlight, Adobe Acrobat and other plugins no longer work? - https://support.mozilla.org/en-US/kb/npapi-plugins

Firefox 52.0 and later Releases have only allowed the NPAPI Flash Player Plugin to run in Firefox.

The old EOL Firefox 52.9.0esr did allow other NPAPI Plugins to run. However for Windows users you needed the 32-bit version to use other Plugins as Win64 Firefox only allowed the Flash Player and Silverlight Plugins to run then. There is also the Java web start

There is also a Java web start that may be an option but that is something I not have used.

https://docs.oracle.com/apps/search/search.jsp?category=java&product=e74273-01&q=java+web+start