Change plugins folder

is there a way to change the folder that my plugins are in? can’t see in preferences > files

There’s no easy way… but see below…
Sketchup always installs RBZ files into the user’s …/AppData/…/Plugins folder - and as it starts it loads the RB files from there [and also an equivalent Plugins folder in your computer’s ProgramData path, if set up, - this is usually set up by rendering extensions, loading the tools for all users on that computer from one source].

However, Fredo wrote a tool which allows you to set up alternative Plugins folders.
The SketchUp sets up and reads in these extra ‘paths’ and loads RB files from there too.
The awkwardness in using this idea comes when installing RBZs into the alternative locations as the Extension Manager doesn’t see the path additions - but it’s possible to do… it involves manually extracting the RBZ archive’s contents and putting them in place in the new location - easy to mess up…
Luckily again there is something to help with this…
If you have an alternative Plugins folder defined and you use the SketchUcation ExtensionStore³ to Auto-Install an RBZ it sees the additional Plugins folder path[s] available [as made by Fredo’s tool etc] and offers those to you from a drop-down list - so if you choose one of those now the RBZ is installed there instead.

The Fredo tool is https://sketchucation.com/pluginstore?pln=000_AdditionalPluginFolders

The ExtensionStore³ is a part of these tools https://sketchucation.com/pluginstore?pln=SketchUcationTools

Generally using the default Plugins folder etc is much easier and less fraught with pitfalls… but it’s up to you…