Hi prashantgupta8055, I have exactly the same situation with my son, and I just went thru all the process to apply PR and OHIP for him. I can share my experience and timelines and helpfully it'll be helpful for you to do the planning.
Previous answers are right - you have to move into Canada and show them you've permanently settled down before you can apply PR for your kid. I have to provide employer letter, my bank statements, my utility bills etc as the evidence. I think you can't just move in and submit the application, you have to live here for quite a few months and collect the evidence.
Your kid has no problem of entering and staying in Canada. I filled out a separate custom card for him when entering, on the card I just said he's a visitor and will stay for 180 days. The CBSA officer did ask me how long he'll be staying, I said he'll be living permanently with us and we'll apply for extension for his stay until he completes the PR process. The officer didn't have more questions.
We submitted PR application for him in July last year. Sydney completed the review in early Jan, and moved to Mississauge office, then they asked for additional docs (basically the utility bills and other docs to show I continued to live in Canada). We got COPR in late Feb, almost 8 months since we submitted the application. We did a flag poling landing immediately. Now we are waiting for his PR card. BTW, his 180 days stay expires in Dec. We submitted an extension application asking for 1 extra year of staying. I just put waiting for PR as the reason, and provided the PR application number. The extension was approved without any question.
Regarding the province medical insurance, it's pretty tricky. Everyone in Service Ontario is confusing about the policy, and I guess they do that case by case. You have to try that in a full service Service Ontario location. There are only a few of them across GTA and they only open Mon-Fri. We reached out to them when I got the letter from CIC that they have "received the application". Service Ontario said they need CIC's "confirmation" (which is COPR I guess, but they didn't say it explicitly). Then I waited until I received the passport collection letter. I received it in early Feb. The letter starts with "The processing of your application for permanent residence in Canada is almost complete. You must complete the following steps within 30 days in order for our office to issue your Confirmation of Permanent Residence and, if applicable, permanent residence visa." I went to Service Ontario again and the lady at the counter still denied my request. I showed her their website. She made a call to back office to check, and the guy on the phone told her it's qualified. So we got the OHIP, but the coverage only starts in 3 months in early May. We're still using private insurance so far. It's not that bad for kids, the premium is like $75 per month, covering only sicks and emergencies, not the vaccine shots.
It's quite a lengthy process and we are still not finished yet. The good side is that there is no absolute obstacle, and you will get the PR for your kid for sure. Good luck!