Here are some activities that can help build social cohesion and establish rapport
Personal Introductions & biographies, live and/or in discussion forum with photos
Welcome videos
A few synchronous/video sessions at the beginning can help build rapport
Office hours and built-in student conferences if applicable
Participation in Discussion
Having an informal group space students can use between sessions.
A more friendly casual tone helps build rapport. Also personalizing communication and showing continuous interest in the individual student greatly helps.
Make room for humor and sharing of personal interests
Respond to students by name in the discussion forum and direct students to each other’s posts
Create study buddies or trios: pair up students manually or using the LMS group tool to support each other during the course.
Conduct ungraded collaborative opportunities for students.
Use polling and small, formative assessments to know about your students, such as their prior knowledge, their personal interests, the kind of technical facilities and skills they have (see Formative Assessment section).
For additional community-building ideas with video demos and additional resources, see this Community-building resource, a growing online resource to support you at the beginning of the semester and throughout.