Sidebar, css

Hello,

I installed oceanwp and I make Site Template with Elementor(in this template i added also Sidebar).Oceanwp->customize–> Sytsle–> I choose single page layout/ w/o sidebar.
Now I would like to change the e.g. Font size of the widgets which are shown in the sidebar. Unfortunately I cannot find any option in elementor. Also several css i try….Can somebody help me?

BR
ben