Macbook specs compatible with Premiere Pro 2018?

If you're cutting 1080p Apple ProRes (any flavor) from a Thunderbolt drive or USB3 drive, you'll be fine; however, you'll have issues with the built-in display at times as it's natively 1280 by 800 and some of the Premiere Pro dialog boxes don't resize.  Fortunately, it supports an external monitor to up to fine 2560 x1600 via DisplayPort Mini.

If you're cutting 2160p Apple ProRes (any flavor), go with the Proxy workflows using 720p Apple ProRes proxies.

Also, you'll be using Software Only for the Mercury Playback Engine.  Things'll work, they'll just take longer.

On the up side, if you're running macOS High Sierra 10.13 or newer, you'll be able to take advantage of the Intel CPU hardware acceleration for H264 encoding.

If you haven't already done it, consider upgrading the Macintosh HD to a 2.5-inch SSD.  Your boot times and application launch times will improve significantly.

-Warren

Short answer: No.

Longer answer: Probably not.

Longest answer: With more free hard drive space and more RAM it might work using proxies.