This quick, 10-minute walkthrough will provide you with the capability to access a lead’s LinkedIn profile from within your lead records.

Easy to accomplish and leverages a record-triggered Flow.

Here is the referenced URL/formula (ensure URL is in a single line):

https://www.linkedin.com/search/results/all/?keywords={!$Record.FirstName}%20{!$Record.LastName}%20{!$Record.Company}

Have fun!