can i work on files from my imac on my laptop

Yes, while you are online, you can download (or pin) files from iCloud Drive to work on while offline. Then "any changes you make to the file will automatically upload to iCloud Drive when you're back online."

Access and manage your files in iCloud Drive - Apple Support

It's very possible and not difficult to set up. You'll want to enable iCloud in each computer so the documents are sync'd and available regardless of which Mac you are using and where. As long as you have internet access your documents will be available.

One consideration will be the version of the app that creates these documents is likely to be different on each computer, so you may have to deal with certain limitation in that regard, but the documents themselves should be accessible. Documents created with newer app versions may not be accessible with older app versions unless steps are taken to convert or specifically save the document in an older format with the newer app.

Anyway, please see: What is iCloud? - Apple Support

And: Set up iCloud on your Mac - Apple Support

The easiest solution is to store you documents in iCloud. Of course, this depends on the size of the documents and how much space you have in iCloud to store documents. It may be worth it to buy additional iCloud storage, as this approach will do what you want with no setup on either device.

The other option is to use Screen Sharing. With this approach you are really only doing the work on the remote computer. It does require a little bit of setup. You will not have the document on both devices, you would only be using the document on the remote device.

Turn Mac screen sharing on or off - Apple Support (AL)

The last option is to use Apple Remote Desktop or purchase a similar program to control the remote device. This is similar to Screen Sharing in that you would just be modifying the document on the remote device. This is more difficult to set up Screen Sharing.

My recommendation is to use iCloud. Even if you have to purchase additional storage, it is only 99 cents a month for 50Gb of storage. You would be using the Applications on each device to modify the same document.

The easiest thing to do, as others have suggested, is to use iCloud. Set up both computers with iCloud and the same AppleID, and store documents that you want to share on iCloud Drive. (Note that if you share your Photos Libraries using iCloud Photos, you'll get to photos using Photos, rather than using iCloud Drive.)

You can sync other things (like your Calendar, Contacts, and Notes) through iCloud, which is pretty handy when using a Mac and an iPhone.

If you're open to using LibreOffice (a free office suite), I believe the current version of it will run on anything from macOS 10.14 Mojave (what you're using now) on up.

https://www.libreoffice.org/

That's one way to address the "app version" issue that Mr.Johnson pointed out. But I believe that in the case of Microsoft Office (or shall I say, Microsoft 365) current versions of the applications probably let you read & save documents using formats known to older versions of Office.

+1 on iCloud.

I use an iMac at home and a Macbook Pro on the road. I've used DropBox for years to work on the same document from either device. I only keep files for current projects there. I can work on a project on the road and, on returning home, have those docs automatically synced to the iMac as soon as I start it without any other action on my part. I've had NO issues.

Some have reported that DropBox takes a performance penalty but I have not seen it, even on slow hotel internet connections. It's possibly due to the fact that I usually have less than 2G of content there.

I will soon be transitioning this function to iCloud because I need more space for an image-heavy project and Dropbox want to sell me a minimum plan of two TB of space— about 40X what I'll ever need—for US$10/month. I can get 50GB storage via iCloud for 1/10th that cost.

Note: To do this file sharing with iCloud, it appears you need to turn on two-factor authentication (2FA)