Reach out to them?

A lot of agents have linkedIn, Facebook, IG etc. I would identify what market you want to get into first. Then I would search social media websites to see who pops up. Do your research and make sure they are a good fit for investors. Not all agents know the investment side of the business. I have a sheet that has 10 questions to ask realtors to see if they are a good fit. I would be more than happy to share if you would like. 

@Eva Brock

Pick up a phone and call them. If they don’t answer or call back not someone you want to work with

Also make sure they are investor focused.

Could be a book on this topic but do research on BP plenty of discussions on this

 Sure I would greatly appreciate the sheet.

Hop on just about any social media platform and start following those agents that work with investors, own investment properties themselves, etc. in the areas you're interested in.  Look on Zillow or Loopnet for listings you're interested in and contact those agents/brokers.  As previously stated by others in this post, call/text/email/msg them.  Anyone like me should respond in a timely manner.  The #1 question you need to ask them is "Do you own (or have you ever owned) any rentals?"  A big mistake I made in the past was using a "Realtor" to help me find investment properties in Las Vegas. She never invested herself or really knew the game at all.  

You want to find an agent who has personally owned investment properties.  They will better understand your desires and needs that a typical residential agent.  Check Zillow or any other online house search platform for reviews.  Call and talk to them.

Be aware that agents get calls from "investors" all the time.  A lot of these calls are from people who just want to look at houses and never pull the trigger.  When you call, be able to discuss what you are looking for and your plans.  If you call and say "I'm looking for a good deal" then they are probably not going to take you seriously (because of course you are).  However, if you call and say you want a "2-4 unit multifamily that only needs minor cosmetic work located near a hospital or university" they will probably be more than happy to help.  Also, get pre-approved or ask who they recommend for pre-approval.

@Eva Brock go to REIA events in your area with your pitch. Normally 1/2 the people at these events are Realtors. Sometimes they'll give you a 2min time to pitch your deals...and the rest will be networking.

If you're at a big brokerage...nationwide type...go to their conferences.  At KW...our big year conference as about 15,000 attendees....so plenty of people to talk to.  Maybe you buy a booth there.  Of course plenty of networking 2-3-4 days all day.

If you're not at a big brokerage that has a big nationwide conference, go to the NAR event or your state event...normally there is a yearly conference.

If your state doesn't have one, go to a difference state....no reason you couldn't go next door.

Offer to speak at a sales meeting for various brokerages with your opportunity...Some brokerages always looking for speakers....same with REIAs and meetups.

I would definitely stay away from sites like Zillow.  But one of the best places to start is right here on Bigger Pockets.  The Active Agents on this platform are going to be more investor centric, and usually possess an in-depth knowledge of real estate investing.  You can also check in Facebook Groups, Meet-up, LinkedIn, TikTok, and Instagram. You may have some luck there.  

You should be going to all the in-person networking events, your local REIA, etc and connecting with all the agents there.

Go to MLS and get the list of the top 25 agents for multifamily/commercial sales in your area. Get their info. Call them, get coffee, and then stalk them on social. Comment on their posts. Learn about them. Start to build those relationships.