There’s the plugin called “Advanced Product Size Charts for WooCommerce” . It’s probably the best plugin for this sort of functionality. It has custom templates, assignment per category etc.
To install, access Appearance > Install Plugins and you should find it listed there. Click on Install and it’ll automatically activate too.
Heads’up! There are a few settings located in Rey theme > Settings > Misc. panel eg: https://d.pr/i/Uxj7JT , to change the button style and position in the product page.