In a plastic bag in the freezer can help - after making sure they’re fully dry. (airing outside is best but obviously in winter this can’t always work out
Clean them and put in some silica gel packets when not in use > less moisture = less bacteria = less smell
Cleaning regularly, cat litter scooping as and when (and a little gel scent neutraliser next to/behind it) bins daily, washing all the sheets, blankets and towels once a week but staggering it (which helps spread fresh linen smell round) and I have some strategically placed reed diffusers (both bathrooms, upstairs hall, downstairs hall, living room) and in the kitchen if I’m cooking something smelly/after I have I have an odour removing candle.
As such I hardly ever need it but I have one general room freshener spray, oust neutraliser spray in both toilets and febreze for the sofas (maybe once a month, if that?)
When I used to have the bin in a cupboard before I got my fancy new kitchen bin I had one of those neutradol gel things in the cupboard with it.