I agree with C, it is a shop and not a house, so the needs are different
My only caution is it will be more energy efficient to run a properly sized unit than to run an undersized unit constantly. A mini split but have to run constantly to heat a space to 50 when it is 0 outside.
Can an HVAC and have him come out price a few options. It will be good, free advice
I keep my thermostat set to 50. Even with the overhead doors opening and closing and some air leaks, it doesn't need to run too much. The concrete floor and all the cast iron do a good job of retaining heat, I think. I will bump it up to 70 an hour before finishing, but them turn it off when I am actually applying finish. I don't want the furnace sucking fumes or blowing dust around. My walls and ceiling are insulated and the garage shares two walls with the house.
Consider your needs. Finishing is the only task that requires true warm for me. Keeping the worst of the chill away is good enough for most things. Glue ups can be set close to the heat source. For most spaces the killer is the inefficiency of the air seal around the garage door.
My understanding is mini splits do an ok job heating in a mild climate, or as supplemental heat. Up north it might not have enough BTU equivalent to warm a 3 car garage on the coldest days. At least that was the advice provided by an HVAC contractor when I added HVAC to the upper level of a prior home.