Hi @orangemarmalade,
Before anything else, about your third question: please don’t delete the site. You don’t need to, and it’s the one step that could lose your images.
- Media
Your Media Library doesn’t belong to the theme. The files live in wp-content/uploads and the entries in the database, so switching themes, or even deleting the old theme afterwards, leaves every image in place, ready to reuse. Only deleting the WordPress site itself (or a host’s “reinstall/reset”) would remove them.
The safe route: Appearance > Themes > Add New > Twenty Twenty-Five, then hover it and click “Live Preview” to look around without switching. When you’re ready, activate it and rebuild page by page; your existing posts and pages stay too. Take a backup first anyway, it’s good practice before any theme change.
What does not carry over from a classic theme: sidebars/widgets, and anything built with that theme’s own shortcodes or page builder. Old menus can be brought back: in the Navigation block’s menu options there’s “Import Classic Menus”.
- Patterns
They’re meant to be used quickly. Twenty Twenty-Five ships about 70 patterns in the inserter (+ > Patterns), grouped as Banners, Featured, Call to action, About, Services, Testimonials, Contact and so on, plus a dozen full-page layouts that appear in a “Choose a pattern” window when you create a new page.
Inserting one is instant. What you get is a copy filled with placeholder text and the theme’s demo images, so the only real “customization” is replacing those with your own. Colors and fonts follow your site styles automatically. So the useful preparation is:
- the text and images for each section, and
- choosing your colors and fonts first (Appearance > Editor > Styles, including the style variations), because every pattern picks them up.
Once you’ve tuned a section you want to repeat, select it and use the three-dot menu > “Create pattern”. If you mark it Synced, editing it once updates it everywhere it’s used.
- Font sizes
- Whole site: Appearance > Editor > Styles > Typography. “Text” sets the body size and “Headings” the heading sizes. “Font size presets” edits the size scale itself (Small to Extra Extra Large), and every block using a preset follows. The theme uses fluid typography, so these sizes also scale down on phones automatically.
- One section or one page: wrap the blocks in a Group (select them, Ctrl/Cmd+G) and set Typography > Size on the Group. Everything inside that doesn’t have its own size inherits it. Headings, and text inside patterns that already have a preset size, keep their own value; change those on the block itself.
Hope that helps you plan the move.
