Excel Essentials
The Complete Excel Series - Level 1, 2 & 3

Think of this as a case of 'just in time learning' - you'll encounter lots more (both in and out of the Excel domain) as you move through the knowledge-work landscape.

I'd recommend independent training resources like Udemy (or Coursera or Edx etc) for this scenario. Without knowing where you are specifically on the skills spectrum, you might try something along the lines of this Udemy course as a potential quick skill-builder. Disclaimer: I've not taken this course myself, but it looks reasonably comprehensive and well-reviewed. If you dedicate a few hours a day to the process of improving this skill, you'll be amazed at what you can accomplish in a relatively short time. If you couple those efforts with some personal projects similar to what you anticipate in your new role, you'll 'level up' quickly.

All that said, I'd recommend against trying to 'BS' your way through anything. Be honest about your skills, current efforts, and level of comfort. If you don't know something, take ownership of learning it in order to provide the sought-after solution. Then learn that thing and come back with quality work that speaks for itself. Any company that is unwilling to work with you while you grow in this way is unworthy of your time and attention. Knowledge work should be symbiotic, not parasitic.

I recognize that dedicating personal time (presumably) to your professional skill-building efforts may be antithetical to the nature of this sub. That said, if this approach helps move you forward, it may be worth considering. Investing in yourself almost always pays off.

I paid for a Udemy course and was extremely happy with the results.

https://www.udemy.com/course/excel-essentials-the-complete-series-levels-1-2-3/