So there are many ways to network - linkedin is one, and local meetups and discussion groups are another.
Covid has made everything a bit of a mess, but there are still ways to "meet" people, typically over zoom/video conerencing.
SO now you know the how (video conferencing if in-person is unavailable to you) and you know the means - linkedin.
What you do is you look at your target companies - google, goldman sachs, wwf, whatever it is - and you find people on linkedin who work in your area at those companies. Then you directly reach out to them and tell them you love working there and you want to apply and can you have a meeting with them?
You don't need to use linkedin - depending on your role/function you can target smaller companies and look at their leadership team (this is generally available on their website) and reach out to the relevant people there. They will often meet with you, or failing that find a suitable person in their team to meet with you.
IF YOU ARE UNLUCKY ENOUGH TO BE AN ENGINEER
Then it gets trickier as engineers clasically lack inter-personal skills and won't understand what is going on. Instead, you would reach out to the people with leadership skills within the engineering department - the higher level (not team leads) managers, the project managers, the sales engineers and the product managers - and ask to talk to them. These people will understand what you are trying to accomplish and will (generally) gladly talk to you and give you advice. They will be thrilled to do this, actually, as it beats talking to engineers.
How you word it:
It works best if you have something in common with the person, and it works best if it is via email (you only would use linkedin to target the person). There are various ways to get emails for people, plugins to chrome etc that you can find.
Then you email them, explain what you have in common (if anything!) - eg, same uni:
"Hi Bob, I'm also a graduate from Great Uni's Business school" and then roll into
"and i'm really exicited about the construction industry. I've loved it ever since I realised how much passion and beauty exist in the space, when I saw the Sagrada Familia in Barcelona." then you discuss their company "I would love to work in the sales department in FantasticCo, I'm really excited about the work you are doing with making-spherical-bricks" finally you ask for an action point "would it be possible to meet with yourself to discuss something I know about and is relevant to fantastic co". As an example: "to discuss how the internal software architecture of fantastic co works to help make these great spherical bricks".
I mean, if you really were going for a sales role that wouldn't be your pitch but you get the general idea. Then you send out a bunch of those, and prepare, and learn more about the thing, and then soon enough you're an expert in how various companies are using thing. Failing that you're met a bunch of leaders and shown you're interested in their field.