Do Not Touch signs help people see that touching could cause injury or damage. Do Not Touch signs are needed whenever a person might hurt themselves or damage equipment by touching it. This includes surfaces, energized electrical parts, newly painted or treated surfaces, equipment that is being fixed delicate instruments and machines that are running.

No. A lockout/tagout tag is part of a hazardous energy control procedure under OSHA 29 CFR 1910.147. It is applied to an energy isolation point when maintenance is active.
Do Not Touch signs are. Placed in a situation to communicate a general rule about contact.

Do Not Touch signs are often seen on hot pipework and steam equipment, on energized electrical panels and exposed conductors, on equipment that is mid‑repair or mid‑inspection, on control settings that should not be changed by unauthorized people, on specimens and samples in laboratories and on new coatings, in manufacturing and finishing areas.

OSHA 29 CFR 1910.145 covers accident‑prevention signs and tags including rules about do not operate and caution tags in maintenance situations. OSHA 29 CFR 1910.303 applies to equipment where contact could cause a shock.
The main hazard: thermal, electrical or chemical, determines which additional standards apply.

Yes. Offices, laboratories, retail shops, food service places and health care facilities also use Do Not Touch signs.Do Not Touch signs are useful whenever touching an item, surface or piece of equipment could create a risk or disturb something that must stay undisturbed.

Adding context makes a sign more useful. “Do Not Touch: Surface" or "Do Not Touch: Equipment Under Repair" tells a worker not just what not to do but why. This improves compliance compared to a sign that only says Do Not Touch.