Can every taxable person opt to pay tax under composition scheme

No, the registered person whose aggregate turnover in the preceding financial year does not exceed seventy-five lakh rupees (subject to fifty lakh rupees in case of specified states as prescribed under Notification 08/2017-Central Tax, dated 28.06.2017), may opt to pay tax subject to satisfaction of the following conditions:
1. he is not engaged in the supply of services other than supplies referred to in clause (b) of paragraph 6 of Schedule II (Restaurant Services);
2. he is not engaged in making any supply of goods which are not leviable to tax under this Act (like petrol, diesel, alcohol liquor for human consumption, etc.);
3. he is not engaged in making any inter-State outward supplies of goods;
4. he is not engaged in making any supply of goods through an electronic
commerce operator who is required to collect tax at source under section 52; and
5. he is not a manufacturer of such goods as may be notified by the Government on the recommendations of the Council:
However, manufacturers of ice cream, pan masala, tobacco and tobacco substitutes are not eligible for composition scheme.

(ICAI FAQ PUBLICATIONS 06-09-2017 COMPOSITION LEVY: FAQ NO. 54)