If the top two posts should be kinda sticky as in the 2 most important posts or whatever instead of being the latest ones or whatever the order is set too, I’d also use 2 query blocks like @digismith said. If not, it’s pretty easy to target the first to posts to change the width. Here is a barebones example which might have to be adapted based on your structure:
.parent-selector .child-post-selector:nth-child(-n+2) {
width: 50%;
}
About the filters and pagination… Haven’t played around with the native filters in Bricks yet but you might wanna consider this related thread: https://forum.bricksbuilder.io/t/no-bug-trouble-with-post-filters/6627